MDCAT 2022 Chemistry

MDCAT 2022 Chemistry Past Paper MCQs with Answers

261 Chemistry MCQs that appeared in MDCAT 2022, arranged unit by unit in syllabus order. Tap “Show answer” under any question for the correct option and a short solution.

Fundamental Concepts of Chemistry

1.What mass is the mass of 2 dm3 of oxygen at S.T.P? (PMC MDCAT 2022)

  1. 1.42 g
  2. 2.22 g
  3. 3.2 g
  4. 2.85 g
Show answer

Correct answer: (d) 2.85 g

$2/22.4$ mole of oxygen at $32\,\mathrm{g\,mol^{-1}}$ weighs about $2.85\,\mathrm{g}$.

2.What is the mass in grams of 1.69 moles of phosphoric acid? (PMC MDCAT 2022)

  1. 148 g
  2. 138 g
  3. 157 g
  4. 166 g
Show answer

Correct answer: (d) 166 g

$1.69\times98$ gives about $166\,\mathrm{g}$.

3.A compound of boron and hydrogen contains 18.9% hydrogen and 81.1% boron. The empirical formula of the compound is: (PMC MDCAT 2022)

  1. BeH2
  2. Be2H
  3. B4H
  4. B2H5
Show answer

Correct answer: (d) B2H5

$81.1/10.8$ to $18.9/1$ is $7.5$ to $18.9$, that is $2$ to $5$.

4.What is the percentage of C in glucose (C6H12O6)? (PMC MDCAT 2022)

  1. 41.5
  2. 38
  3. 39.9
  4. 38.9
Show answer

Correct answer: (c) 39.9

Carbon is $72$ of the $180$ units of the molar mass, that is about $40\%$.

5.One mole of ethanol and one mole of ethane have an equal: (NUMS MDCAT 2022)

  1. Mass
  2. Number of atoms
  3. Number of electrons
  4. Number of molecules
Show answer

Correct answer: (d) Number of molecules

A mole of anything holds Avogadro’s number of molecules.

6.The 1' step involved in the determination of Empirical Formula of chemical compound is: (NUMS MDCAT 2022)

  1. Finding number of gram atoms of each element
  2. Percentage composition of each element
  3. Atomic ratio of each element
  4. Multiplication of atomic ratio with whole number
Show answer

Correct answer: (b) Percentage composition of each element

The analysis gives the percentage of each element, and everything else follows from that.

7.The number of moles of CO2 which contains 16 g of oxygen is: (NUMS MDCAT 2022)

  1. 0.25
  2. 0.5
  3. 1
  4. 2
Show answer

Correct answer: (b) 0.5

Sixteen grams is one mole of oxygen atoms, and each molecule carries two, so there is half a mole.

8.Percentage composition of mass in CO2, is: (NUMS MDCAT 2022)

  1. 30.45% Carbon & 69.54% Oxygen
  2. 24.22% Carbon & 75.78% Oxygen
  3. 27.37% Carbon & 72.72% Oxygen
  4. 41.68% Carbon & 58.12% Oxygen
Show answer

Correct answer: (c) 27.37% Carbon & 72.72% Oxygen

Carbon is $12$ of the $44$ units, that is $27.3\%$, and the oxygen is the rest.

9.30 grams of ethanol are mixed with excess acidified $\mathrm{K_2Cr_2O_7}$ and boiled under reflux. The organic product is collected by distillation and the yield is 75.0%. What is the mass of product produced? (MDCAT 2022)

  1. 1.74 g
  2. 24.75 g
  3. 2.74 g
  4. 29 g
Show answer

Correct answer: (d) 29 g

$30/46=0.65$ mol of ethanol would give $0.65\times60=39$ g of ethanoic acid, and 75% of that is about 29 g.

10.The amount of product according to the balanced chemical equation is called as? (PMC MDCAT 2022)

  1. Theoretical yield
  2. Actual amount
  3. Limiting amount
  4. Stoichiometric amount
Show answer

Correct answer: (a) Theoretical yield

The amount the equation says is possible is the theoretical yield.

11.In a particular chemical reaction the actual yield was 70gm, while that of Its theoretical yield Is 100gm. The pecentage yield of the said reatlon is: (PMC MDCAT 2022)

  1. 100%
  2. 70%
  3. 40%
  4. 20%
Show answer

Correct answer: (b) 70%

$70/100$ is a yield of $70\%$.

12.The limiting reactant in a particular chemical reaction is the one which: (PMC MDCAT 2022)

  1. Is consumed later in the reaction
  2. Is present in excess in the reaction
  3. Gives the least amount of product
  4. Gives the largest amount of product
Show answer

Correct answer: (c) Gives the least amount of product

The limiting reactant is used up first and so fixes how much product can be made.

13.The amount of reactant according to the balanced chemical equation is called as? (PMC MDCAT 2022)

  1. Excess amount
  2. Actual amount
  3. Limiting amount
  4. Stoichiometric amount
Show answer

Correct answer: (d) Stoichiometric amount

The amount the equation calls for is the stoichiometric amount.

14.The ________ reagent is the reactant that gets consumed first in a chemical reaction and therefore limits how much product can be formed. (PMC MDCAT 2022)

  1. excess
  2. limiting
  3. extent
  4. none of the above
Show answer

Correct answer: (b) limiting

The reactant used up first is the limiting reagent.

15.Which one of the following is calculated from balanced equation during the determination of limiting reactant? (PMC MDCAT 2022)

  1. Amount of reactants present
  2. Amount of limiting reactant that produces·the product
  3. Amount of product expected to form from each reactant
  4. Amountof excess reactant
Show answer

Correct answer: (c) Amount of product expected to form from each reactant

Each reactant is converted to the product it could give, and the smaller answer settles which is limiting.

16.In the process of iron rusting, which of the following is the limiting reactant? (PMC MDCAT 2022)

  1. Iron
  2. Oxygen
  3. Air
  4. Water
Show answer

Correct answer: (a) Iron

Air supplies oxygen and water without limit, so it is the iron that runs out.

Atomic Structure

17.Which gas in a discharge tube produces the lightest canal ray particles? (MDCAT 2022)

  1. Ar
  2. He
  3. $\mathrm{H_2}$
  4. Ne
Show answer

Correct answer: (c) $\mathrm{H_2}$

The positive rays are ions of the gas, and the hydrogen ion, the proton, is the lightest of them.

18.Mass of electron ___ times smaller than that of proton. (PMC MDCAT 2022)

  1. 1837
  2. 1839
  3. 1836
  4. 1834
Show answer

Correct answer: (c) 1836

The proton is about $1836$ times as massive as the electron.

19.In the gaseous phase, when ionization takes place ____________ are isolated and are free from all external influences: (PMC MDCAT 2022)

  1. Atoms and molecule
  2. Atom and cation
  3. Atom and anion
  4. Atom and ion
Show answer

Correct answer: (b) Atom and cation

Ionization energy is measured in the gas phase, where an isolated atom gives an isolated cation.

20.Who named the positive rays produced by the hydrogen gas in discharge tube? (PMC MDCAT 2022)

  1. Goldstein
  2. Rutherford
  3. Bohr
  4. Chedwick
Show answer

Correct answer: (b) Rutherford

Rutherford identified the positive ray of hydrogen as a new particle and named it the proton.

21.In the discharge tube positive rays moves in which direction (PMC MDCAT 2022)

  1. Towards anode
  2. Towards cathode
  3. Move randomly
  4. Move towards vaccum in the tube
Show answer

Correct answer: (b) Towards cathode

Positive rays are cations, so they are drawn to the negative electrode.

22.Proton number of 23Na11 is: (NUMS MDCAT 2022)

  1. 23
  2. 11
  3. 12
  4. 34
Show answer

Correct answer: (b) 11

The subscript is the atomic number, so sodium has eleven protons.

23.The mass of electron is: (NUMS MDCAT 2022)

  1. 1836 times more than mass of proton
  2. 1836 times less than mass of proton
  3. 1836 times more than mass of neutron
  4. 1836 times more than mass of hydrogen atom
Show answer

Correct answer: (b) 1836 times less than mass of proton

The proton is about $1836$ times as massive as the electron.

24.What is the value of Planck’s constant {h)? (PMC MDCAT 2022)

  1. 6.62×10^-34Js
  2. 6.02×10^-34Js
  3. 6.62×10^-33Js
  4. 6.34×10^-34 Js
Show answer

Correct answer: (a) 6.62×10^-34Js

Planck’s constant is $6.62\times10^{-34}\,\mathrm{J\,s}$.

25.Which is the correct demonstration of de-Broglie equation? (PMC MDCAT 2022)

  1. λ=mv/h
  2. λ=h/mv
  3. h=λ/mv
  4. P=λ/h
Show answer

Correct answer: (b) λ=h/mv

De Broglie put the wavelength of a particle at $h/mv$.

26.According to which scientist is the probability of finding an electron at a certain position possible? (MDCAT 2022)

  1. Bohr
  2. de Broglie
  3. Hund
  4. Schrodinger
Show answer

Correct answer: (d) Schrodinger

The square of the wave function of the Schrodinger equation gives the probability of finding the electron in a region, which is what an orbital is.

27.Which of the following orbital is closer to the nucleus? (PMC MDCAT 2022)

  1. 3d
  2. 2p
  3. 3p
  4. 3s
Show answer

Correct answer: (b) 2p

The lower the principal quantum number the nearer the shell, and 2p is nearer than any of the third shell.

28.How many electrons are present in the orbital having n=1, l=0, m=0? (PMC MDCAT 2022)

  1. 3
  2. 2
  3. 4
  4. 5
Show answer

Correct answer: (b) 2

Those numbers name the 1s orbital, which holds two electrons of opposite spin.

29.Which subshells are present In M shell? (PMC MDCAT 2022)

  1. s
  2. s, p
  3. s, p, d
  4. s, p, d, f
Show answer

Correct answer: (c) s, p, d

The third shell has $l=0,1,2$, that is s, p and d.

30.The maximum number of electrons which can be accommodated in all orbital for which I=3 is: (PMC MDCAT 2022)

  1. 6
  2. 14
  3. 10
  4. 18
Show answer

Correct answer: (b) 14

With $l=3$ there are seven orbitals, holding fourteen electrons.

31.The value of Azimuthal quantum number (I) depends upon: (PMC MDCAT 2022)

  1. n
  2. m
  3. s
  4. p
Show answer

Correct answer: (a) n

For a given $n$ the azimuthal number runs from $0$ to $n-1$.

32.Maximum electrons that can be placed in p subshell are: (NUMS MDCAT 2022)

  1. 2
  2. 6
  3. 10
  4. 14
Show answer

Correct answer: (b) 6

A p subshell has three orbitals, holding six electrons.

33.The shape of an orbital is determined by which quantum number? (NUMS MDCAT 2022)

  1. n
  2. l
  3. m
  4. s
Show answer

Correct answer: (b) l

The azimuthal quantum number $l$ fixes the shape.

34.Which principle contradicts the Bohr’s model? (PMC MDCAT 2022)

  1. Planck quantum theory
  2. Hunds rule
  3. Pauli's exclusion principle
  4. Heisenberg's uncertainty principle
Show answer

Correct answer: (d) Heisenberg's uncertainty principle

Bohr gave the electron a definite orbit and speed, which the uncertainty principle forbids.

35.What is the shape of s-orbital ? (PMC MDCAT 2022)

  1. Lobed
  2. Spherical
  3. Dumbbell
  4. Sausage
Show answer

Correct answer: (b) Spherical

An s orbital is spherical about the nucleus.

36.Which element has the ground state electronic configuration $1s^2\,2s^2\,2p^6\,3s^2\,3p^6$? (MDCAT 2022)

  1. Ar
  2. O
  3. Na
  4. S
Show answer

Correct answer: (a) Ar

Eighteen electrons filling up to $3p$ is argon.

37.How many unpaired electrons are there in the Nitrogen atom? (PMC MDCAT 2022)

  1. 3
  2. 4
  3. 5
  4. 6
Show answer

Correct answer: (a) 3

Nitrogen is $1s^2 2s^2 2p^3$, and by Hund’s rule the three p electrons stay unpaired.

38.The valence shell electronic configuration of Ca is Ar[ ]: (PMC MDCAT 2022)

  1. 1s2
  2. 2s2
  3. 3s2
  4. 4s2
Show answer

Correct answer: (d) 4s2

Calcium is $[\mathrm{Ar}]4s^2$.

39.Which of the following atomic orbital has lowest energy? (PMC MDCAT 2022)

  1. 1s
  2. 2p
  3. 3s
  4. 4p
Show answer

Correct answer: (a) 1s

The 1s orbital is nearest the nucleus and lowest in energy.

40.Atomic numbers of chromium (Cr) is 24. Correct electronic configuration of Cr is: (PMC MDCAT 2022)

  1. [Ar]3d54s1
  2. [Ar]3d54s2
  3. [Ar]3d04s0
  4. [Ar]3d44s2
Show answer

Correct answer: (a) [Ar]3d54s1

A half filled d subshell is stable, so chromium is $[\mathrm{Ar}]3d^5 4s^1$.

41.How many electrons does calcium have in the 3p orbital? (PMC MDCAT 2022)

  1. 5
  2. 6
  3. 2
  4. 3
Show answer

Correct answer: (b) 6

Calcium is $[\mathrm{Ne}]3s^2 3p^6 4s^2$, so its 3p subshell is full with six.

42.The atomic number of calcium is 20. The electronic structure of a calcium ion can be represented as: (PMC MDCAT 2022)

  1. 2,8
  2. 2,8,4
  3. 2,8,8
  4. 2,8,8,2
Show answer

Correct answer: (c) 2,8,8

The calcium ion has lost its two 4s electrons, leaving the argon structure 2,8,8.

43.Apply n+l rule and calculate which of the following orbital has maximum energy? (NUMS MDCAT 2022)

  1. 4s
  2. 2p
  3. 2d
  4. 3s
Show answer

Correct answer: (a) 4s

The 4s orbital has the largest $n+l$ of these, so it lies highest.

Gases

44.The process of heat flow between hotter and colder gases continues until all the molecules have equal: (MDCAT 2022)

  1. average translational kinetic energy
  2. average rotational kinetic energy
  3. average translational potential energy
  4. average vibrational kinetic energy
Show answer

Correct answer: (a) average translational kinetic energy

Temperature measures the average translational kinetic energy, and heat flows until the two gases share it equally.

45.According to the kinetic molecular theory, collisions between the gas molecues: (PMC MDCAT 2022)

  1. Are elastic
  2. Are non-elastic
  3. Increase energy
  4. Decrease energy
Show answer

Correct answer: (a) Are elastic

Collisions between gas molecules are perfectly elastic, so no kinetic energy is lost.

46.Spreading of scent in the air is due to: (PMC MDCAT 2022)

  1. Diffusion of gas molecules
  2. Effusion of gas molecules
  3. Volume of gas
  4. Temperatue of gas
Show answer

Correct answer: (a) Diffusion of gas molecules

The molecules of the scent move at random and spread through the air, which is diffusion.

47.Gases can easily mix with each other to form a uniform mixture, this property Is called: (PMC MDCAT 2022)

  1. Effusion
  2. Homogenous Mixing
  3. Diffusion
  4. Heterogenous mixing
Show answer

Correct answer: (c) Diffusion

The spontaneous intermingling of gases is diffusion.

48.Standard temperatue in Fahrenheit {°F) is: (PMC MDCAT 2022)

  1. -273°F
  2. 0°F
  3. 32°F
  4. 114°F
Show answer

Correct answer: (c) 32°F

Standard temperature is $0^{\circ}\mathrm{C}$, that is $32^{\circ}\mathrm{F}$.

49.1 atm is equal to the following EXCEPT: (PMC MDCAT 2022)

  1. 760 mm of Hg
  2. 76 cm of Hg
  3. 760 torr
  4. 1.47 psi
Show answer

Correct answer: (d) 1.47 psi

One atmosphere is $14.7\,\mathrm{psi}$, not $1.47$.

50.The quantitative relationship between absolute temperature (T) and volume (V) of a fixed amount of a gas at constant pressure (P) can be best described by: (PMC MDCAT 2022)

  1. VT=K
  2. V / P = T
  3. V/T =K
  4. P=KT
Show answer

Correct answer: (c) V/T =K

At constant pressure the volume is proportional to the absolute temperature, so $V/T$ is constant.

51.The product of volume and pressure of fixed amount of a gas at constant temperature remains same for initial and final state of a gaseous system. This statement corresponds to: (PMC MDCAT 2022)

  1. Avogadro's Law
  2. Dalton's law
  3. Boyle's law
  4. Graham's law
Show answer

Correct answer: (c) Boyle's law

That is Boyle’s law.

52.The temperature at which volume of all the ideal gases becomes zero is: (PMC MDCAT 2022)

  1. 0 K
  2. 0˚C
  3. 0˚F
  4. 32˚F
Show answer

Correct answer: (a) 0 K

Extrapolating the volume line of any gas to zero brings it to absolute zero.

53.Which of the following represents equation for ideal gas? (NUMS MDCAT 2022)

  1. PV=nRT
  2. PT=nRv
  3. P=nRT
  4. T=npv/R
Show answer

Correct answer: (a) PV=nRT

The ideal gas equation is $PV=nRT$.

54.How should the condition be changed to prevent the value of a given gas from expanding when its mass is increased? (NUMS MDCAT 2022)

  1. Temperature is lowered & pressure is increased
  2. Temperature is increased & pressure is lowered
  3. Temperature & pressure both are lowered
  4. Temperature & pressure both are increased
Show answer

Correct answer: (a) Temperature is lowered & pressure is increased

More moles would push the volume up, so the temperature must be lowered and the pressure raised to hold it.

55.Which variable mentioned in ideal gas is assumed to be constant in other gas laws? (NUMS MDCAT 2022)

  1. Volume
  2. Temperature
  3. Pressure
  4. Number of moles
Show answer

Correct answer: (d) Number of moles

Boyle’s, Charles’s and the pressure law all hold for a fixed mass of gas.

56.If we want to raise the temperature of one mole of an ideal gas by one kelvin, how much energy do we have to provide? (MDCAT 2022)

  1. 0.0821 joules
  2. $8.314\ \mathrm{dm^3\,atm}$
  3. 0.0821 kJ
  4. $0.0821\ \mathrm{dm^3\,atm}$
Show answer

Correct answer: (d) $0.0821\ \mathrm{dm^3\,atm}$

That energy is the gas constant itself, $R=8.314\ \mathrm{J\,mol^{-1}K^{-1}}=0.0821\ \mathrm{dm^3\,atm\,mol^{-1}K^{-1}}$.

57.The value of general gas constant ‘R’ for a particular gas is independant of: (PMC MDCAT 2022)

  1. Pressure
  2. Volume
  3. Absolute temperature
  4. Molar mass of the gas.
Show answer

Correct answer: (d) Molar mass of the gas.

$R$ is the same for every gas, which is why it is called the universal gas constant.

58.Intermolecular forces between gas molecules are significant at: (PMC MDCAT 2022)

  1. High temperature and low pressure
  2. Low temperature and high pressure
  3. At standard temperature and pressure
  4. At high temperature and high pressure
Show answer

Correct answer: (b) Low temperature and high pressure

Cooling and compressing bring the molecules close and slow, so their attractions begin to tell.

59.Which of the following postulate of kinetic molecular theory does NOT hold at high temperature and pressure? (PMC MDCAT 2022)

  1. Gases are considered to be composed of minute discrete particles called molecules.
  2. The molecules move in straight line.
  3. The pressure of gas is produced due to the collision of molecules with the wall of container.
  4. The volume occupied by the gas molecules is negligible as compared to the the total volume of the gas.
Show answer

Correct answer: (d) The volume occupied by the gas molecules is negligible as compared to the the total volume of the gas.

Squeezed close, the molecules take up a real fraction of the volume, and that is the assumption that fails.

60.Which one of the following is called as compressibility factor? (PMC MDCAT 2022)

  1. PV=nRT
  2. PV/nRT
  3. PV/RT=n
  4. PV/T=Rn
Show answer

Correct answer: (b) PV/nRT

$PV/nRT$ is the compressibility factor, one for an ideal gas and something else for a real one.

61.Gases behave ideally at: (PMC MDCAT 2022)

  1. under normal temperature and pressure conditions
  2. at room temperature and pressure
  3. at high temperature and low pressure
  4. at high pressure and low temperature
Show answer

Correct answer: (c) at high temperature and low pressure

Hot and thin, the molecules are far apart and moving fast, so their attractions and their own volume hardly count.

Liquids

62.Specific heat of water is: (NUMS MDCAT 2022)

  1. 4.18 J/g/°C
  2. 9.82 J/g/°C
  3. 6.04 J/g/°C
  4. 8.47 J/g/°C
Show answer

Correct answer: (a) 4.18 J/g/°C

Water takes $4.18\,\mathrm{J}$ to raise a gram by a degree.

63.Which of the following statement explains solubility of ionic substance in water? (NUMS MDCAT 2022)

  1. Water molar mass is 18.02
  2. Water forms dative bonding
  3. Water molecule is polar
  4. Water has high density
Show answer

Correct answer: (c) Water molecule is polar

Water molecules are polar, so they pull the ions apart and surround them.

64.Which of the following factors does not affect the vapour pressure of a liquid? (MDCAT 2022)

  1. amount of liquid
  2. size of molecules
  3. temperature of the liquid
  4. intermolecular forces
Show answer

Correct answer: (a) amount of liquid

Vapour pressure is an intensive property; a larger volume of the same liquid at the same temperature has the same vapour pressure.

65.Which of the following molecules will show a higher rate of evaporation? (NUMS MDCAT 2022)

  1. Acetone
  2. Ethanol
  3. Water
  4. Ethylene glycol
Show answer

Correct answer: (a) Acetone

Acetone has the weakest intermolecular forces of the four, so it evaporates fastest.

66.Which of the following substances has the largest intermolecular forces of attraction? (PMC MDCAT 2022)

  1. H2O
  2. H2S
  3. H2Se
  4. H2Te
Show answer

Correct answer: (a) H2O

Water alone hydrogen bonds; the others are held only by dipole and dispersion forces.

Solids

67.The solid which is hardest of all types is _____? (PMC MDCAT 2022)

  1. Covalent solids
  2. Molecular solids
  3. Ionic solids
  4. Metallic solids
Show answer

Correct answer: (a) Covalent solids

A covalent network such as diamond is bonded right through, so it is the hardest kind of solid.

68.Which of the following properties of isomorphs is NOT true? (PMC MDCAT 2022)

  1. lsomorphs can make homogeneous mixtures together
  2. Have different physical properties
  3. Have same atoms
  4. Have same ratio of atoms
Show answer

Correct answer: (c) Have same atoms

Isomorphs have the same crystal shape and the same ratio of atoms, but the atoms themselves differ.

69.Polymorphs have same (PMC MDCAT 2022)

  1. Chemical Properties
  2. Melting points
  3. Structures
  4. boiling points
Show answer

Correct answer: (a) Chemical Properties

Polymorphs are the same substance in different crystal forms, so their chemistry is the same.

70.The repetition of faces, angles and edges of a crystal, when it is rotated to 360 degree angle is called: (PMC MDCAT 2022)

  1. Habit of crystal
  2. Isomorphism
  3. Symmetry
  4. Polymorphism
Show answer

Correct answer: (c) Symmetry

The repetition of faces and edges on turning is the symmetry of the crystal.

71.Which of the following crystal has highest density? (PMC MDCAT 2022)

  1. Iodine
  2. Graphite
  3. Ice
  4. Sodium Chloride
Show answer

Correct answer: (a) Iodine

Iodine is much the heaviest of these for its volume, so its crystal is the densest.

72.The properties which depends upon the direction are called: (PMC MDCAT 2022)

  1. Isotropic properties
  2. Anisotropic properties
  3. Additive properties
  4. Colligative properties
Show answer

Correct answer: (b) Anisotropic properties

A property that differs with the direction taken through the crystal is anisotropic.

73.Which of the following solid has indefinite heat of fusion? (PMC MDCAT 2022)

  1. Crystalline solids
  2. Pure solids
  3. True solids
  4. Amorphous solids
Show answer

Correct answer: (d) Amorphous solids

An amorphous solid has no fixed melting point, so it has no definite heat of fusion.

74.The following are anisotropic properties except: (PMC MDCAT 2022)

  1. Refractive Index
  2. Thermal conductivtiy
  3. Electrical conductivity
  4. Melting points
Show answer

Correct answer: (d) Melting points

A melting point is one number for the whole crystal, so it cannot vary with direction.

75.Malleability is a property of metals which means_____? (PMC MDCAT 2022)

  1. Drawn into wires
  2. Converted into sheets
  3. Drawn into wires and converted into sheets
  4. Breakable
Show answer

Correct answer: (b) Converted into sheets

Malleable means it can be beaten into sheets; ductile means it can be drawn into wire.

76.Which solids are also called as atomic solids? (PMC MDCAT 2022)

  1. Ionic solids
  2. Covalent solids
  3. Molecular solids
  4. Metallic solids
Show answer

Correct answer: (b) Covalent solids

A covalent network such as diamond is one giant molecule of atoms, so it is called an atomic solid.

77.Who proposed valence bond theory for metals? (PMC MDCAT 2022)

  1. Loren
  2. Drudge
  3. L.Pauling
  4. Maxwell
Show answer

Correct answer: (c) L.Pauling

Pauling put forward the valence bond account of metallic bonding.

78.Which of the following Is not true about Polymorphs? (PMC MDCAT 2022)

  1. Have same chemical properties
  2. lnterconvertible
  3. Have same formula unlt
  4. Have different formula unit
Show answer

Correct answer: (d) Have different formula unit

Polymorphs are the same compound in different crystal forms, so their formula unit is the same.

79.A solid compounds exists is more than one crystalline form, this phenomenon is called (PMC MDCAT 2022)

  1. Allotropy
  2. Isomorphism
  3. Polymorphism
  4. Isomerism
Show answer

Correct answer: (c) Polymorphism

One compound crystallizing in more than one form is polymorphism.

80.Which of the following solids shows the phenomenal of Isomorphism? (PMC MDCAT 2022)

  1. Molecular Solids
  2. Covalent solids
  3. Ionic solids
  4. Metallic solids
Show answer

Correct answer: (c) Ionic solids

Ionic solids of similar formula and ion size crystallize in the same form, which is isomorphism.

81.Nature of diamond as solid is: (NUMS MDCAT 2022)

  1. Covalent
  2. Ionic
  3. Molecular
  4. Metallic
Show answer

Correct answer: (a) Covalent

Diamond is a covalent network of carbon atoms bonded right through the crystal.

82.Which one of the following is as light as a feather and as strong as iron? (NUMS MDCAT 2022)

  1. Graphite
  2. Graphene
  3. Mercury
  4. Diamond
Show answer

Correct answer: (b) Graphene

Graphene is a single sheet of graphite, almost weightless and stronger than steel.

83.The smallest block which carries the whole information about a crystal structure is called the: (MDCAT 2022)

  1. cell
  2. unit cell
  3. crystal lattice
  4. crystal unit
Show answer

Correct answer: (b) unit cell

Repeating the unit cell in three dimensions builds the whole lattice.

84.Position of atoms in molecular crystals can be determined by: (PMC MDCAT 2022)

  1. X-rays analysis
  2. Spectroscopic analysis
  3. Spectrometric analysis
  4. Combustlon analysis
Show answer

Correct answer: (a) X-rays analysis

X-ray diffraction is what reveals the arrangement of the atoms in a crystal.

85.What shapes does diamond and NaCl unit cells possess? (PMC MDCAT 2022)

  1. NaCl monoclinic and diamond cubic
  2. NaCl cubic and diamond rhombic
  3. Both are cubic
  4. Both are rectangular
Show answer

Correct answer: (c) Both are cubic

Both crystallize in the cubic system.

86.The array of points which shows the atoms ions or molecule arrangements in a crystal is called. (PMC MDCAT 2022)

  1. Crystal system
  2. Crystal lattice
  3. Crystal array
  4. Crystallography
Show answer

Correct answer: (b) Crystal lattice

The regular array of points representing the particles is the crystal lattice.

87.Born Haber cycle is used to determine: (PMC MDCAT 2022)

  1. Enthalpy of lattice
  2. Enthalpy of formation
  3. Enthalpy of Neutralisation
  4. Enthalpy of Solution
Show answer

Correct answer: (a) Enthalpy of lattice

The Born-Haber cycle gives the lattice energy, which cannot be measured directly.

88.What is the value of lattice energy when one mole of an ionic crystal is formed? (PMC MDCAT 2022)

  1. Positive value
  2. Negative value
  3. Zero value
  4. Positive fraction value
Show answer

Correct answer: (b) Negative value

Energy is released when the gaseous ions come together, so the lattice energy is negative.

89.Lattice energy does not depend on the: (PMC MDCAT 2022)

  1. Nature of charge of the ion
  2. Size of ions
  3. Magnitude of charge on the ion
  4. Room temperature
Show answer

Correct answer: (d) Room temperature

Lattice energy turns on the charges and sizes of the ions; the temperature of the room does not enter.

Chemical Equilibrium

90.[Product]/[Reactant] = 2.5 for a reaction at equilibrium, what does it mean? (PMC MDCAT 2022)

  1. Products are more than reactants
  2. Products are Less
  3. reaction is at equilibrium
  4. Reactants are more
Show answer

Correct answer: (a) Products are more than reactants

A ratio above one means the equilibrium lies on the side of the products.

91.For a particular reversible reaction If [Products]/[Reactants]>Kc It means that: (PMC MDCAT 2022)

  1. More products are needed to attain equillbrium
  2. There are more reactants in the system
  3. More Reactants are needed to attain equillbrium
  4. The reaction will move forward to attain equilibrium
Show answer

Correct answer: (c) More Reactants are needed to attain equillbrium

The quotient is above the constant, so the reaction must run backwards to reach equilibrium.

92.One can estimate the direction in which an equilibrium will shift with the help of: (MDCAT 2022)

  1. Le Chatelier's principle
  2. the law of mass action
  3. Hess's law
  4. the law of heat of formation
Show answer

Correct answer: (a) Le Chatelier's principle

The system responds so as to reduce the change imposed on it, which is Le Chatelier's principle.

93.Precipitation occurs if the ionic concentration is: (MDCAT 2022)

  1. greater than $K_{sp}$
  2. less than $K_{sp}$
  3. equal to $K_{sp}$
  4. present in any amount
Show answer

Correct answer: (a) greater than $K_{sp}$

The solution can hold only as much as $K_{sp}$ allows, so anything above that comes out as solid.

94.Ksp (Solubility product) depends upon: (PMC MDCAT 2022)

  1. Pressure
  2. Concentration
  3. Temperature
  4. Volume
Show answer

Correct answer: (c) Temperature

Like any equilibrium constant, the solubility product changes only with temperature.

95.Which term describes a solution in which dissolved solute is in equilibrium with undissolved solute? (NUMS MDCAT 2022)

  1. Dilute
  2. Saturated
  3. Unsaturated
  4. Supersaturated
Show answer

Correct answer: (b) Saturated

A saturated solution is one in equilibrium with the undissolved solid.

96.The decrease in solubility of a salt in a solution that already contains an ion common to that salt is known as: (MDCAT 2022)

  1. Le Chatelier's principle
  2. solubility product
  3. common ion effect
  4. $K_{sp}$
Show answer

Correct answer: (c) common ion effect

The added common ion shifts the dissolution equilibrium back towards the solid.

97.When Hydrogen Chloride gas passes through saturated brine, it increases the concentration of: (PMC MDCAT 2022)

  1. Sodium ion
  2. Hydrogen ion
  3. Calcium ion
  4. Chloride ion
Show answer

Correct answer: (d) Chloride ion

The added chloride is the ion common to the salt, so it drives the sodium chloride out of solution.

98.Common Ion Effect finds its extensive application in: (PMC MDCAT 2022)

  1. quantitative analysis
  2. Gas testing
  3. material testing
  4. Salt analysis
Show answer

Correct answer: (d) Salt analysis

The salts of a group are precipitated by adding a common ion, which is how they are separated.

99.What will happen to the KClO3 when KCl is added to its solution in water? (PMC MDCAT 2022)

  1. Its solubility increases
  2. Its solubility decreases
  3. Concentration of Cl- ion decreases
  4. Concentration of ClO3- ion increases
Show answer

Correct answer: (b) Its solubility decreases

The potassium ion is common to both salts, so it drives the chlorate out of solution.

100.The reaction of a weak acid and its salt with a strong base produces: (PMC MDCAT 2022)

  1. Basic buffer
  2. A buffer with pH <7
  3. Neutral buffer
  4. Amphoteric buffer
Show answer

Correct answer: (b) A buffer with pH <7

A weak acid with its salt is an acidic buffer, holding a pH below seven.

101.The pH of a solution can be kept constant by: (PMC MDCAT 2022)

  1. saturated solution
  2. super saturated solution
  3. buffer solution
  4. dilute solution
Show answer

Correct answer: (c) buffer solution

A buffer resists a change of pH when a little acid or alkali is added.

102.Which of the following solutions will act as a buffer? (PMC MDCAT 2022)

  1. HN02 and NaN02
  2. HCI and KCI
  3. HN03 and NH4N03
  4. NaOH and NaCl
Show answer

Correct answer: (a) HN02 and NaN02

Nitrous acid with its sodium salt is a weak acid and its conjugate base, which is a buffer.

103.The pH of an acidic buffer depends upon the concentration of acid, concentration of salt and: (PMC MDCAT 2022)

  1. pKa of acid used in it
  2. pH of acid used in it.
  3. pKb of base used in it
  4. pOH of base used in it.
Show answer

Correct answer: (a) pKa of acid used in it

The Henderson equation gives the pH as the $\mathrm{p}K_a$ plus the log of the salt to acid ratio.

104.Addition of extra CH3COONa in acetate buffer soluton wlll: (PMC MDCAT 2022)

  1. Decrease pH
  2. Have no effect on pH
  3. Increase pH
  4. First increases, then decreases
Show answer

Correct answer: (c) Increase pH

More salt raises the ratio of acetate to acid, so the pH rises.

105.The addition of an acid or H+ Ions to acetic acid buffer will: (PMC MDCAT 2022)

  1. Increase the pH
  2. Decrease the pH
  3. Have no effect on the pH
  4. Both A and B
Show answer

Correct answer: (c) Have no effect on the pH

The acetate ions take up the added protons, so the pH scarcely moves.

106.The pH of human blood is: (NUMS MDCAT 2022)

  1. 7.35 to 7.45
  2. 8.35 to 8.45
  3. 6.35 to 7.45
  4. 5.57 to 6.57
Show answer

Correct answer: (a) 7.35 to 7.45

Blood is held between pH $7.35$ and $7.45$ by its buffers.

107.Nitrogen and Hydrogen present in equilibrium mixture in Haber Process remain in (PMC MDCAT 2022)

  1. Solid state
  2. Liquid state
  3. Gaseous state
  4. Mixture of solid and gas
Show answer

Correct answer: (c) Gaseous state

The synthesis is run at about $450^{\circ}\mathrm{C}$, well above the boiling point of all three gases.

Reaction Kinetics

108.Activation energy for forward and backward reaction is always: (PMC MDCAT 2022)

  1. Same
  2. Different
  3. Reciprocal of each other
  4. Higher for forward reaction
Show answer

Correct answer: (b) Different

The two barriers differ by the enthalpy of the reaction.

109.At ordinary temperature, only few molecules possess energy equal to (PMC MDCAT 2022)

  1. Kinetic energy
  2. Potential Energy
  3. Activation energy
  4. Ionization Energy
Show answer

Correct answer: (c) Activation energy

Only the small fraction of molecules at the top of the energy distribution can react.

110.A catalyst which is in the same phase as the reactants is known as: (MDCAT 2022)

  1. a heterogeneous catalyst
  2. a homogeneous catalyst
  3. a slow catalyst
  4. a fast catalyst
Show answer

Correct answer: (b) a homogeneous catalyst

One phase throughout is what homogeneous means.

111.Number of molecules possessing Ea (Activation Energy) can be increased by (PMC MDCAT 2022)

  1. Adding a catalyst
  2. increasing the volume
  3. increasing temperature
  4. increasing temperature of Moles of Reactants
Show answer

Correct answer: (c) increasing temperature

Heating spreads the energies upwards, so a far larger fraction of molecules clears the barrier.

112.The slowest reaction among these is (PMC MDCAT 2022)

  1. Neutralization
  2. Double Decomposition Reactions
  3. Ionic Reactions
  4. Hydrogenation Reaction
Show answer

Correct answer: (d) Hydrogenation Reaction

Hydrogenation needs bonds broken and a catalyst; ionic reactions need only a meeting of ions.

113.Rate of any reaction depends upon: (NUMS MDCAT 2022)

  1. Temperature
  2. Concentration
  3. Pressure
  4. Rate constant
Show answer

Correct answer: (a) Temperature

Raising the temperature speeds almost every reaction, and steeply.

114.What is "NOT TRUE" about rate of a reaction? (NUMS MDCAT 2022)

  1. Concentration of reactants does not affect the rate of a reaction
  2. Surface area of reactants affects rate of reaction
  3. Concentration affects rate of reaction
  4. Catalyst affects rate of a reaction
Show answer

Correct answer: (a) Concentration of reactants does not affect the rate of a reaction

Concentration does affect the rate; that is what the rate law says.

115.The number of reactant molecules whose concentrations affect the rate of reaction is called: (PMC MDCAT 2022)

  1. Rate law
  2. Molecularity
  3. Order of reaction
  4. Rate constant
Show answer

Correct answer: (b) Molecularity

The number of molecules taking part in the rate determining step is the molecularity.

116.The reaction in which rate depends only on one reactant concentrations, although more than one reactants are present in the reaction mixture is known as __________ (PMC MDCAT 2022)

  1. 1st order reaction
  2. 2nd order reaction
  3. Pseudo first order reaction
  4. Third order reaction
Show answer

Correct answer: (c) Pseudo first order reaction

With one reactant in great excess its concentration hardly changes, so the reaction behaves as first order.

117.The rate law of a particular reaction is Rate = k[NO][O3]. The order of this reaction with respect to ozone is: (PMC MDCAT 2022)

  1. 1st
  2. 2nd
  3. 3rd
  4. Zero
Show answer

Correct answer: (a) 1st

Ozone appears to the first power, so the order in it is one.

118.Arrhenius equation is an equation of: (PMC MDCAT 2022)

  1. Curve
  2. Parabola
  3. Straight line
  4. Hyperbola
Show answer

Correct answer: (c) Straight line

Taking logarithms turns it into $\ln k=\ln A-E_a/RT$, a straight line against $1/T$.

119.What Is the unit of slope obtained from Arrhenius equation? (PMC MDCAT 2022)

  1. K
  2. J/mol K
  3. mol/K
  4. K-
Show answer

Correct answer: (a) K

The slope is $-E_a/R$, and joules per mole over joules per mole per kelvin leaves kelvin.

Thermochemistry and Energetics of Chemical Reactions

120.In the air, N2 and O2 occur naturally but they do not react to form oxides of nitrogen because: (PMC MDCAT 2022)

  1. Oxides of nitrogen are unstable
  2. Catalyst is required for the reaction
  3. The reaction is endothermic
  4. N2 and O2 do not react with each other
Show answer

Correct answer: (c) The reaction is endothermic

Nitrogen and oxygen combine only at the temperature of a spark or an engine, because the reaction absorbs heat.

121.Enthalpy change of combustion is exothermic because: (NUMS MDCAT 2022)

  1. Energy released in bond breaking is greater
  2. Energy released in bond making is greater
  3. Energy absorbed in bond breaking is greater
  4. Energy absorbed in bond making is greater
Show answer

Correct answer: (b) Energy released in bond making is greater

More energy comes out in forming the new bonds than goes in breaking the old ones.

122.Which of the following terms is a state function? (MDCAT 2022)

  1. freezing
  2. decomposition
  3. sublimation
  4. enthalpy
Show answer

Correct answer: (d) enthalpy

Enthalpy depends only on the state of the system, not on the path by which it got there.

123.One Calorie is equivalent to: (NUMS MDCAT 2022)

  1. 4.184 J
  2. 4.184 kJ
  3. 0.4184 J
  4. 0.4184 kJ
Show answer

Correct answer: (a) 4.184 J

One calorie is $4.184\,\mathrm{J}$.

124.The Born-Haber cycle is used to determine the lattice energy of ionic compounds. It is an application of: (MDCAT 2022)

  1. Henry's law
  2. Le Chatelier's principle
  3. Hess's law
  4. the common ion effect
Show answer

Correct answer: (c) Hess's law

The cycle adds the enthalpies of a set of steps to reach the same final state, which is Hess's law.

125.Which of the following law Is an application of first law of thermodynamics? (PMC MDCAT 2022)

  1. Hess's law
  2. Dalton's law
  3. Moseley's Law
  4. Avogadro's law
Show answer

Correct answer: (a) Hess's law

Hess’s law follows from the conservation of energy applied to enthalpy.

126.The correct value for the enthalpy of formation of CO is: (PMC MDCAT 2022)

  1. -110kJ/mol
  2. -210kJ/mol
  3. +110kJ/mol
  4. +210kJ/mol
Show answer

Correct answer: (a) -110kJ/mol

Carbon monoxide is formed from its elements with the release of about $110\,\mathrm{kJ\,mol^{-1}}$.

127.Which one of the following is the correct demonstration of first law of thermodynamics? (PMC MDCAT 2022)

  1. △H= qw
  2. △E=q – P△V
  3. △H=q+w
  4. △E = q+w
Show answer

Correct answer: (d) △E = q+w

The first law is $\Delta E=q+w$.

Electrochemistry

128.An electrochemical cell is based upon which reaction? (MDCAT 2022)

  1. acid-base reaction
  2. redox reaction
  3. nuclear reaction
  4. neutralization reaction
Show answer

Correct answer: (b) redox reaction

The cell works by separating the oxidation and the reduction, so the electrons travel through the external circuit.

129.Fe is precipitated out when Mg strip is dipped in (PMC MDCAT 2022)

  1. FeSO4 solution
  2. CuSO4 Solution
  3. MgSO4 Solution
  4. H2SO4 solution
Show answer

Correct answer: (a) FeSO4 solution

Magnesium is above iron in the reactivity series, so it displaces iron from the solution.

130.Which of the following substances is the strongest reducing agent? (PMC MDCAT 2022)

  1. Cl2
  2. Cl-
  3. Br2
  4. Br-
Show answer

Correct answer: (d) Br-

A reducing agent gives up electrons, and the bromide ion parts with one most readily here.

131.A galvanic cell is setup (PMC MDCAT 2022)

  1. When a less reactive metal contacts a more reactive metal via an electrolyte
  2. When two reactive metals contact via an electrolyte
  3. When two reactive metals are placed in any solutiin
  4. When two metals come In direct contact
Show answer

Correct answer: (a) When a less reactive metal contacts a more reactive metal via an electrolyte

A galvanic cell needs two metals of different reactivity joined through an electrolyte.

132.In which of the following does oxygen show a fractional oxidation number? (MDCAT 2022)

  1. $\mathrm{OF_2}$
  2. $\mathrm{Na_2O_2}$
  3. $\mathrm{KO_2}$
  4. $\mathrm{Cl_2O_7}$
Show answer

Correct answer: (c) $\mathrm{KO_2}$

In the superoxide $\mathrm{KO_2}$ the two oxygens share a single negative charge, so each is $-\tfrac{1}{2}$.

133.Which statement describes the conversion of magnesium atoms to magnesium ions for ionic bond formation with chlorine? (MDCAT 2022)

  1. the change is reduction, because there has been a gain of electrons
  2. the change is oxidation, because there has been a loss of electrons
  3. the change is reduction, because there has been a loss of electrons
  4. the change is oxidation, because there has been a gain of electrons
Show answer

Correct answer: (b) the change is oxidation, because there has been a loss of electrons

Mg loses two electrons to become $\mathrm{Mg^{2+}}$, and loss of electrons is oxidation.

134.Oxidation state of Cr in K2Cr207 is: (PMC MDCAT 2022)

  1. +3
  2. +4
  3. +5
  4. +6
Show answer

Correct answer: (d) +6

Two potassium at $+1$ and seven oxygen at $-2$ leave $+12$ for two chromium atoms, so each is $+6$.

135.In the electrolysis of fused salt, where do the cations move? (PMC MDCAT 2022)

  1. Move towards anode and discharge on it
  2. Move towards cathode and discharge on it
  3. Move towards cathod, gain electron and dissolve in solution
  4. Both a and b
Show answer

Correct answer: (b) Move towards cathode and discharge on it

Cations are attracted to the cathode, where they take electrons and are discharged.

136.Electrons flow from _____ (PMC MDCAT 2022)

  1. Anode to cathode
  2. Cathode to anode
  3. Don't flow
  4. In either directions
Show answer

Correct answer: (a) Anode to cathode

Electrons leave the electrode where oxidation happens, the anode, and travel to the cathode.

137.During electrolysis, reduction always occurs at: (NUMS MDCAT 2022)

  1. Anode
  2. Cathode
  3. SHE
  4. Salt bridge
Show answer

Correct answer: (b) Cathode

Reduction is gain of electrons, and the electrons enter at the cathode.

138.In the ion-electron method of balancing equations, how oxygen is balanced? (PMC MDCAT 2022)

  1. O is balanced by adding O2
  2. O is balanced by adding H2O
  3. O is balanced by adding OH
  4. All the ways are used
Show answer

Correct answer: (b) O is balanced by adding H2O

Oxygen is balanced by adding water to the side short of it, and hydrogen then by adding protons.

139.Cu ion takes up 2 electrons to give an electrode potential value of: (PMC MDCAT 2022)

  1. +0.76 v
  2. -0.32 v
  3. +0.34 v
  4. -0.34 v
Show answer

Correct answer: (c) +0.34 v

The standard electrode potential of the copper half cell is $+0.34\,\mathrm{V}$.

140.What is the advantage of using a platinaum foil in the standard hydrogen electrode formation? (PMC MDCAT 2022)

  1. It acts as catalyst
  2. It does not support the electrode
  3. It provides a large surface area
  4. It decreases the time duration for measurement
Show answer

Correct answer: (a) It acts as catalyst

Platinized platinum catalyses the change between hydrogen gas and its ions at the surface.

141.The element has highest reduction potential in electrochemical series Is; (PMC MDCAT 2022)

  1. Zinc
  2. Fluorine
  3. Oxygen
  4. Lithium
Show answer

Correct answer: (b) Fluorine

Fluorine is the strongest oxidizing agent, so it stands at the top of the series.

142.Cu, Au and Ag are least reactive, because they have _____ ? (PMC MDCAT 2022)

  1. Negative reduction potential
  2. Negative oxidation potential
  3. Positive reduction potential
  4. Negative electrode potential
Show answer

Correct answer: (c) Positive reduction potential

A positive reduction potential means the metal holds its electrons and is not readily oxidized.

143.Potential of Standard Hydrogen Electrode (SHE) is arbitrarily taken as: (NUMS MDCAT 2022)

  1. 10
  2. +1
  3. -1
  4. Zero
Show answer

Correct answer: (d) Zero

The hydrogen electrode is taken as zero and everything else is measured against it.

Chemical Bonding

144.Which of the following does not have a complete octet? (PMC MDCAT 2022)

  1. O2-
  2. N5+
  3. Ca2+
  4. K+
Show answer

Correct answer: (b) N5+

Nitrogen stripped of five electrons is left with only two, so it has no octet.

145.In which of the following functional groups is the carbon atom $sp$ hybridized? (MDCAT 2022)

  1. $-\mathrm{CHO}$
  2. $-\mathrm{COOH}$
  3. $-\mathrm{CN}$
  4. $-\mathrm{COOR}$
Show answer

Correct answer: (c) $-\mathrm{CN}$

The carbon of the nitrile group holds a triple bond, so it is $sp$ hybridized and linear.

146.How many hybrdized orbitals are formed by intermixing of 4 atomic orbitals? (PMC MDCAT 2022)

  1. 2
  2. 4
  3. 8
  4. 6
Show answer

Correct answer: (b) 4

Hybridization gives back as many orbitals as it mixes, so four atomic orbitals give four hybrids.

147.In the structure of diamond, each carbon atom is ____ hybridized? (PMC MDCAT 2022)

  1. sp3
  2. sp2
  3. sp
  4. dsp2
Show answer

Correct answer: (a) sp3

Each carbon in diamond is bonded tetrahedrally to four others, so it is sp3.

148.Sp3 hybridization is also called as: (PMC MDCAT 2022)

  1. Sigma
  2. Pi bond
  3. Coordinate covalent
  4. Hydrogen bond
Show answer

Correct answer: (a) Sigma

All four sp3 orbitals overlap head-on, so every bond they make is a sigma bond.

149.Type of hybridization of carbon in Ethene (H2C=CH2) is: (NUMS MDCAT 2022)

  1. Sp3
  2. sp2
  3. Sp
  4. dsp2
Show answer

Correct answer: (b) sp2

Each carbon of ethene makes three sigma bonds and one pi bond, so it is sp2.

150.The pi bonds surrounding the sigma bonds in an ethyne molecule are in the shape of: (PMC MDCAT 2022)

  1. Linear
  2. Cylindrical
  3. Trigonal Planar
  4. Tetrahedral
Show answer

Correct answer: (b) Cylindrical

The two pi bonds of ethyne at right angles make a cylinder of charge round the axis.

151.Pi (π) bond between two atoms is (PMC MDCAT 2022)

  1. Formed by axial overlapping of atomic orbitals, and is stronger than sigma bond.
  2. Formed by parallel overlapping of atomic orbitals, and is stronger than sigma bond.
  3. Formed by axial overlapping of atomic orbitals, and is weaker than sigma bond.
  4. Formed by parallel overlapping of atomic orbitals, and is weaker than sigma bond.
Show answer

Correct answer: (d) Formed by parallel overlapping of atomic orbitals, and is weaker than sigma bond.

A pi bond is the sideways overlap of two p orbitals, and that overlap is poorer than the head-on one of a sigma bond.

152.Which of the following orbitals has lower energy? (PMC MDCAT 2022)

  1. Anti-bonding molecular orbital
  2. Anti-bonding atomic orbitals
  3. Bonding half-filled orbitals
  4. Bonding molecular orbital
Show answer

Correct answer: (d) Bonding molecular orbital

The bonding molecular orbital lies below the atomic orbitals it was made from.

153.An $\mathrm{AB_4}$ type molecule with no lone pairs has which shape? (MDCAT 2022)

  1. trigonal
  2. regular tetrahedron
  3. regular octahedron
  4. regular pyramid
Show answer

Correct answer: (b) regular tetrahedron

Four bond pairs and nothing else repel to the corners of a tetrahedron, $109.5^\circ$ apart.

154.Select among the following that has trigonal pyramidal geometry: (PMC MDCAT 2022)

  1. NH3
  2. BF3
  3. AlCl3
  4. SO3
Show answer

Correct answer: (a) NH3

Ammonia has three bond pairs and one lone pair, so its shape is trigonal pyramidal.

155.If bond energy of C-CI is 346 kJ/mol. The bond enegy of C-Br should be: (PMC MDCAT 2022)

  1. 290 kJ/mol
  2. 390 kJ/mol
  3. 490 kJ/mol
  4. 590 KJ/mol
Show answer

Correct answer: (a) 290 kJ/mol

Bromine is the larger atom, so its bond to carbon is longer and weaker.

156.The amount of energy required to beak one mole of a particular type of bond is equal to its: (PMC MDCAT 2022)

  1. Activation energy
  2. Ionization energy
  3. Bond Energy
  4. Potential energy
Show answer

Correct answer: (c) Bond Energy

That energy is the bond energy.

157.Which of these has a bond length of ______ 174 pm? (PMC MDCAT 2022)

  1. C-C
  2. Cl-Cl
  3. Cl-H
  4. C-Cl
Show answer

Correct answer: (d) C-Cl

The carbon chlorine bond is about $174\,\mathrm{pm}$, the sum of the two covalent radii.

158.When repulsive forces tend to push the atoms apart and the potential energy of the system is_______ (PMC MDCAT 2022)

  1. No Effect
  2. Decrease
  3. Increase
  4. Change in alternation
Show answer

Correct answer: (c) Increase

Pushed closer than the bond length, the atoms repel and the energy of the system climbs steeply.

159.Which type of bond is present between C and O in methanol? (PMC MDCAT 2022)

  1. Dative bond
  2. Polar bond
  3. Non-Polar bond
  4. Ionic bond
Show answer

Correct answer: (b) Polar bond

Oxygen is much the more electronegative, so the shared pair is drawn towards it.

160.Which of the following molecule is covalent in nature? (NUMS MDCAT 2022)

  1. NaCl
  2. MgCl2
  3. AlCl3
  4. KCl
Show answer

Correct answer: (c) AlCl3

Aluminium has a small, highly charged ion that polarizes the chloride, so the bond is largely covalent.

161.Which of the following molecule is polar? (NUMS MDCAT 2022)

  1. CCl4
  2. AlCl3
  3. CO2
  4. HCl
Show answer

Correct answer: (d) HCl

Hydrogen chloride is a single polar bond with nothing to cancel it; the other three are symmetrical.

s- and p-Block Elements

162.More the ionization potential, the less will be the ability to form: (PMC MDCAT 2022)

  1. Cations
  2. Anions
  3. Radicals
  4. Free radicals
Show answer

Correct answer: (a) Cations

A high ionization energy means the atom holds its electrons tightly and will not readily give one up.

163.Which statement about the Group VIA elements is false? (PMC MDCAT 2022)

  1. All have an outer electronic configuration of ns2np4
  2. The electronegativity of Group VIA elements decreases as one goes down the group
  3. Most are found in sulfide deposits
  4. Oxygen has the highest boiling point and melting point
Show answer

Correct answer: (d) Oxygen has the highest boiling point and melting point

Melting and boiling points rise down the group, so oxygen has the lowest, not the highest.

164.The covalent radius of H2 is: (PMC MDCAT 2022)

  1. 37.7 pm
  2. 37.7 nm
  3. 37.7 mm
  4. 37.7μm
Show answer

Correct answer: (a) 37.7 pm

Half the bond length in the hydrogen molecule is about $37.7\,\mathrm{pm}$.

165.Shielding effect in 3rd period of periodic table: (PMC MDCAT 2022)

  1. Increases from left to right.
  2. Decreases from left to right.
  3. May increase or decrease
  4. Remain unchanged
Show answer

Correct answer: (d) Remain unchanged

The inner shells do not change across a period, so the screening they give stays the same.

166.In alkali metals the highest shielding effect is exhibited by: (PMC MDCAT 2022)

  1. Li
  2. Na
  3. K
  4. Rb
Show answer

Correct answer: (d) Rb

Screening grows with the number of inner shells, and rubidium has the most of these four.

167.Which of the following has highest atomic size? (PMC MDCAT 2022)

  1. Be
  2. Mg
  3. Ca
  4. Ba
Show answer

Correct answer: (d) Ba

Atomic radius grows down the group, and barium is the lowest of the four.

168.Using the periodic table, indicate which one of the following elements is the most metallic? (PMC MDCAT 2022)

  1. Rb
  2. K
  3. Ca
  4. Fe
Show answer

Correct answer: (a) Rb

Metallic character grows down a group and falls across a period, and rubidium is lowest and furthest left.

169.Covalant radius is defined as half of the single bonded length between _____ atoms covalently bonded in a molecule. (PMC MDCAT 2022)

  1. Two Different
  2. Two Simultaneous
  3. Any Two
  4. Two Similar
Show answer

Correct answer: (c) Any Two

Covalent radius is half the distance between the nuclei of two like atoms singly bonded.

170.Among alkali metals which of the following property is high for Li? (PMC MDCAT 2022)

  1. Hydration energy
  2. Ionic radius
  3. Electropositivity
  4. Atomic size
Show answer

Correct answer: (a) Hydration energy

The lithium ion is the smallest, so water molecules pack tightly round it and much energy is released.

171.Electron affinity decreases down the group because: (NUMS MDCAT 2022)

  1. Proton number increases
  2. Atomic radius increases
  3. Shielding decrease
  4. Rate constant
Show answer

Correct answer: (b) Atomic radius increases

The bigger the atom, the further the added electron is from the nucleus.

172.Galvanised Iron sheets have a coating of ___________. (PMC MDCAT 2022)

  1. Tin
  2. Silver
  3. Zinc
  4. Chromium
Show answer

Correct answer: (c) Zinc

Galvanizing is coating iron with zinc, which corrodes in its place.

173.The name of a common ore from which aluminium can be extracted is called? (PMC MDCAT 2022)

  1. Charcoal
  2. Haematite
  3. Bauxite
  4. Cryolite
Show answer

Correct answer: (c) Bauxite

Bauxite is the hydrated oxide from which aluminium is extracted.

174.Which of the following products is formed by the reaction of aluminium with nitrogen? (PMC MDCAT 2022)

  1. AlN3
  2. AlN
  3. Al2N2
  4. Al3N2
Show answer

Correct answer: (b) AlN

Aluminium burns in nitrogen to the nitride, $\mathrm{AlN}$.

175.Which of the following metal occurs in free state __________ ? (PMC MDCAT 2022)

  1. Gold
  2. Iron
  3. Mercury
  4. Copper
Show answer

Correct answer: (a) Gold

Gold is so unreactive that it is found as the metal itself.

176.The Halide of aluminum is ___ ? (PMC MDCAT 2022)

  1. Electron deficient
  2. Lewis acid
  3. High melting point
  4. High boiling point
Show answer

Correct answer: (b) Lewis acid

Aluminium has only six electrons round it in the halide, so it accepts a pair and acts as a Lewis acid.

177.NaCl can be purified by passing gaseous ________. (PMC MDCAT 2022)

  1. Sulfuric acid
  2. Chlorine
  3. Ammonia
  4. Hydrogen Chloride
Show answer

Correct answer: (d) Hydrogen Chloride

Hydrogen chloride raises the chloride concentration and salts the sodium chloride out.

178.Which of the following metal is highly reactive? (PMC MDCAT 2022)

  1. Li
  2. Zn
  3. Ag
  4. Au
Show answer

Correct answer: (a) Li

Lithium is an alkali metal and by far the most reactive of these four.

179.Upon burning in air, normal oxide is formed by: (PMC MDCAT 2022)

  1. Li
  2. Na
  3. K
  4. Rb
Show answer

Correct answer: (a) Li

Lithium alone gives the simple oxide; the heavier alkali metals give peroxides and superoxides.

180.Alkali metal oxides dissolve In water to give: (PMC MDCAT 2022)

  1. Alkaline solution
  2. Neutral solution
  3. Acidic solution
  4. Buffer solution
Show answer

Correct answer: (a) Alkaline solution

The oxide takes up water to give the hydroxide, which is a strong alkali.

181.Which of the following property increases down the group in alkali metals? (NUMS MDCAT 2022)

  1. Ionization energy
  2. Reactivity
  3. Electron affinity
  4. Electronegativity
Show answer

Correct answer: (b) Reactivity

The outer electron is easier to lose down the group, so the metal grows more reactive.

182.Which of the following sulphates is insoluble in water? (MDCAT 2022)

  1. $\mathrm{BeSO_4}$
  2. $\mathrm{BaSO_4}$
  3. $\mathrm{MgSO_4}$
  4. $\mathrm{CaSO_4}$
Show answer

Correct answer: (b) $\mathrm{BaSO_4}$

Solubility of the group II sulphates falls down the group, and barium sulphate is insoluble.

183.All alkaline earth metals react with nitrogen to give: (PMC MDCAT 2022)

  1. Nitrates
  2. Nitrides
  3. Nitriles
  4. Amides
Show answer

Correct answer: (b) Nitrides

Heated in nitrogen, the group II metals form nitrides of formula $\mathrm{M_3N_2}$.

184.When magnesium nitride (Mg3 N2 ) reacts with with water the reaction mixture becomes: (PMC MDCAT 2022)

  1. Acidic
  2. Basic
  3. Neutral
  4. Amphoteric
Show answer

Correct answer: (b) Basic

The nitride hydrolyses to magnesium hydroxide and ammonia, both of them alkaline.

185.Which of the following does not react with water even at red hot temperature. (PMC MDCAT 2022)

  1. BeO
  2. MgO
  3. CaO
  4. BaO
Show answer

Correct answer: (a) BeO

Beryllium oxide is covalent and inert; the oxides below it in the group give hydroxides with water.

186.Which one of the following is more soluble in water? (PMC MDCAT 2022)

  1. Be{OH)2
  2. Ca(OH)2
  3. Mg(OH)2
  4. Ba(OH)2
Show answer

Correct answer: (d) Ba(OH)2

Solubility of the group II hydroxides rises down the group, so barium hydroxide is the most soluble.

187.Among alkaline earth metals the one which shows the least chemical reactivity Is: (PMC MDCAT 2022)

  1. Be
  2. Ca
  3. Mg
  4. Ba
Show answer

Correct answer: (a) Be

Beryllium is the smallest of the group and its compounds are largely covalent, so it reacts least readily.

188.The solubility of alkaline earth metal: (NUMS MDCAT 2022)

  1. Decreases down the group
  2. Increases down the group
  3. Remains constant throughout the group
  4. First increases then decreases down the group
Show answer

Correct answer: (b) Increases down the group

The hydroxides grow more soluble down group II as the lattice energy falls faster than the hydration energy.

189.Which group of the periodic table contains non-metals, metalloids and metals? (MDCAT 2022)

  1. IB
  2. VIIA
  3. IVA
  4. IIA
Show answer

Correct answer: (c) IVA

Group IVA runs from carbon, a non-metal, through silicon and germanium, metalloids, to tin and lead, metals.

190.Which of the following has anti-knocking properties? (PMC MDCAT 2022)

  1. (CH3CH2)4Sn
  2. (CH3CH2)4Pb
  3. (CH3CH2)4Ge
  4. (CH3CH2)4Si
Show answer

Correct answer: (b) (CH3CH2)4Pb

Tetraethyl lead was added to petrol to stop it knocking.

Transition Elements

191.In which pair does one element have all unpaired $d$ orbitals while the other has all paired $d$ orbitals? (MDCAT 2022)

  1. Cu and Zn
  2. Cr and Fe
  3. Cr and Zn
  4. Mn and Co
Show answer

Correct answer: (c) Cr and Zn

Chromium is $3d^5$, with every $d$ orbital singly filled, and zinc is $3d^{10}$, with every one of them full.

192.Coinage metals belong to which group of the periodic table? (PMC MDCAT 2022)

  1. 1B
  2. 2B
  3. 3B
  4. 3A
Show answer

Correct answer: (a) 1B

Copper, silver and gold make up group IB.

193.An element that forms interstitial compounds is ______. (PMC MDCAT 2022)

  1. C
  2. F
  3. Cs
  4. Rb
Show answer

Correct answer: (a) C

Small atoms such as carbon fit into the holes of a metal lattice to give interstitial compounds.

194.Which element shows maximum oxidation state? (PMC MDCAT 2022)

  1. Cu
  2. Zn
  3. Cr
  4. Mn
Show answer

Correct answer: (d) Mn

Manganese can use all seven of its outer electrons, so it reaches $+7$.

195.The transition element which shows fixed 2+ oxidation state in its compound is: (PMC MDCAT 2022)

  1. Zn
  2. Fe
  3. Cu
  4. Mn
Show answer

Correct answer: (a) Zn

Zinc has a full d subshell, so it can only lose its two 4s electrons.

196.The color of Zn2+ compounds is: (PMC MDCAT 2022)

  1. Yellow
  2. Black
  3. Blue
  4. Colorless
Show answer

Correct answer: (d) Colorless

Zinc has no partly filled d subshell, so there are no d-d transitions and its salts are white.

197.How many unpaired electrons are there in Co2+ ion? (PMC MDCAT 2022)

  1. 2
  2. 3
  3. 4
  4. 7
Show answer

Correct answer: (b) 3

Cobalt(II) is $3d^7$, which leaves three electrons unpaired.

198.Transition elements form which bond with ligands? (PMC MDCAT 2022)

  1. Covalent
  2. Ionic
  3. Metallic
  4. Coordinate Covalent
Show answer

Correct answer: (d) Coordinate Covalent

The ligand donates both electrons of the bond to the empty d orbital of the metal.

Fundamental Principles of Organic Chemistry

199.Which of the following is not an IUPAC name of the compound? (PMC MDCAT 2022)

  1. Methanoic acid
  2. Ethanoic acid
  3. Propanoic acid
  4. Propionic acid
Show answer

Correct answer: (d) Propionic acid

Propionic acid is the trivial name; the systematic one is propanoic acid.

200.Which one of the following is not a common name? (PMC MDCAT 2022)

  1. Butanoic acid
  2. Formic acid
  3. Propionic acid
  4. Acetic acid
Show answer

Correct answer: (a) Butanoic acid

Butanoic acid is the systematic name; the others are the older trivial names.

201.The compounds containing the $\mathrm{R-SH}$ functional group are known as: (MDCAT 2022)

  1. alcohols
  2. thio-alcohols
  3. thio-ethers
  4. nitriles
Show answer

Correct answer: (b) thio-alcohols

Sulphur in the place of the oxygen of an alcohol gives a thio-alcohol, or thiol.

202.Which of the following is an oxonium ion? (PMC MDCAT 2022)

  1. NH4+
  2. PH4+
  3. RSH2+
  4. H3O+
Show answer

Correct answer: (d) H3O+

The hydronium ion is an oxonium ion, oxygen with three bonds and a positive charge.

203.The covalent compounds exhibit: (PMC MDCAT 2022)

  1. Fast reactions
  2. Non-directional nature
  3. Non-rigid structures
  4. lsomerism
Show answer

Correct answer: (d) lsomerism

A covalent bond points in a definite direction, so the same atoms can be arranged in more than one way.

204.Geometric isomerism is exhibited by: (NUMS MDCAT 2022)

  1. Alcohol
  2. Ethers
  3. Alkynes
  4. Alkenes
Show answer

Correct answer: (d) Alkenes

A double bond cannot rotate, so the groups on either side are fixed as cis or trans.

Chemistry of Hydrocarbons

205.Consider the chlorination of methane. The attack of a chlorine free radical on methane to form a methyl free radical occurs in the: (MDCAT 2022)

  1. initiation step
  2. propagation step
  3. termination step
  4. last step
Show answer

Correct answer: (b) propagation step

One radical is consumed and another is produced, which is what keeps the chain going.

206.Halogenation of alkane in sunlight is an example of: (PMC MDCAT 2022)

  1. Addition reaction
  2. Elimination reaction
  3. Substitution reaction
  4. Rearrangment reaction
Show answer

Correct answer: (c) Substitution reaction

A hydrogen of the alkane is replaced by a halogen, which is substitution.

207.The termination step of the Halogenation of alkanes in the presence of sunlight involves the formation of: (PMC MDCAT 2022)

  1. Free radicals
  2. Cations
  3. Anions
  4. Molecules
Show answer

Correct answer: (d) Molecules

Two radicals meeting join into a molecule, and the chain ends there.

208.Major product of the following reaction is: CH2=CH-CH2-CH3 + HBr -> (PMC MDCAT 2022)

  1. CH2 (Br)-CH2 -CH2 -CH3
  2. CH3-CH(Br)-CH2-CH3
  3. CH2=CH-CH(Br)-CH3
  4. CH2=CH-CH2-CH2(Br)
Show answer

Correct answer: (b) CH3-CH(Br)-CH2-CH3

By Markovnikov’s rule the bromine adds to the carbon already carrying more substituents.

209.The three alternate double bonds in benzene are called: (MDCAT 2022)

  1. delocalized bonds
  2. coordinate covalent bonds
  3. fixed bonds
  4. ionic bonds
Show answer

Correct answer: (a) delocalized bonds

The six $p$ electrons spread over all six carbons, so the bonds are delocalized rather than three fixed double bonds.

210.The ratio of sigma to pi electrons in benzene is: (MDCAT 2022)

  1. 2 : 3
  2. 5 : 1
  3. 4 : 1
  4. 1 : 4
Show answer

Correct answer: (c) 4 : 1

Benzene has twelve sigma bonds, so 24 sigma electrons, against 6 pi electrons.

211.What is the structure of benzene? (PMC MDCAT 2022)

  1. Regular, flat planar hexagon
  2. Regular, 3D hexagon
  3. Regular, flat planar octagon
  4. Regular, planar pentagon
Show answer

Correct answer: (a) Regular, flat planar hexagon

Benzene is a flat regular hexagon with all six bonds of the same length.

212.The C-C bond length in benzene is: (PMC MDCAT 2022)

  1. 1.39 Angstrom
  2. 1.20 Angstrom
  3. 1.34 Angstrom
  4. 1.54 Angstrom
Show answer

Correct answer: (a) 1.39 Angstrom

Every carbon carbon bond in benzene is $1.39\,\text{\AA}$, between a single and a double bond.

213.Alkylbenzene is formed when benzene is treated with an alkyl halide in the presence of anhydrous aluminium chloride. Identify the type of reaction. (MDCAT 2022)

  1. halogenation
  2. Friedel-Crafts acylation
  3. Friedel-Crafts alkylation
  4. sulphonation
Show answer

Correct answer: (c) Friedel-Crafts alkylation

An alkyl group substitutes for a ring hydrogen with the Lewis acid as catalyst.

214.A new C-C bond formation is possible with: (PMC MDCAT 2022)

  1. Clemmensen reaction
  2. Nitration reaction
  3. Friedel craft reaction
  4. Saturation reaction
Show answer

Correct answer: (c) Friedel craft reaction

Friedel-Crafts alkylation and acylation both make a new bond from the ring carbon to carbon.

215.Which of the following process gives Benzenesulfonic acid from benzene? (PMC MDCAT 2022)

  1. Ozonolysis
  2. Sulphonation
  3. Nitration
  4. Halogenation
Show answer

Correct answer: (b) Sulphonation

Fuming sulphuric acid substitutes a sulphonic acid group into the ring.

216.What is the Catalyst in Friedel-Crafts Alkylation? (PMC MDCAT 2022)

  1. AlCl3
  2. Al2S3
  3. AlH3
  4. Al2O3
Show answer

Correct answer: (a) AlCl3

Anhydrous aluminium chloride generates the carbocation that attacks the ring.

217.Which of the following undergoes sulfonation the fastest? (PMC MDCAT 2022)

  1. Benzene
  2. Chlorobenzene
  3. Nitrobenzene
  4. Toluene
Show answer

Correct answer: (d) Toluene

The methyl group feeds electrons into the ring and so speeds up attack by the electrophile.

218.Conversion of straight chain hydrocarbons into branched chain is called as __________. (PMC MDCAT 2022)

  1. Reforming
  2. Cracking
  3. lsomerization
  4. Decomposition
Show answer

Correct answer: (a) Reforming

Reforming rearranges straight chains into branched and cyclic ones of higher octane number.

219.Which of the following fraction of petroleum has the lowest boiling point at STP. (PMC MDCAT 2022)

  1. Kerosene oil
  2. Lubricating oil
  3. Gasoline
  4. Heavy Oil
Show answer

Correct answer: (c) Gasoline

The lighter the fraction the lower it boils, and gasoline is the lightest of these.

220.Fuels with higher octane number can be produced by_ _ ? (PMC MDCAT 2022)

  1. Cracking
  2. Reforming
  3. Decomposition
  4. lsomerisation
Show answer

Correct answer: (a) Cracking

Reforming turns straight chains into branched and aromatic ones, which resist knocking.

221.The breaking of large molecules by heating at high temperature and pressure is called: (PMC MDCAT 2022)

  1. Reforming
  2. Steam cracking
  3. Catalytic cracking
  4. Thermal cracking
Show answer

Correct answer: (d) Thermal cracking

Breaking the chains by heat alone is thermal cracking.

222.Which of the following fractions of petroleum has the lowest boiling point at STP? (PMC MDCAT 2022)

  1. Kerosene Oil
  2. Lubricating Oil
  3. Gasoline
  4. Natural Gas
Show answer

Correct answer: (d) Natural Gas

Natural gas is the lightest fraction of all and boils lowest.

223.Which of the following compounds is more acidic? (MDCAT 2022)

  1. alkane
  2. alkene
  3. alkyne
  4. cycloalkane
Show answer

Correct answer: (c) alkyne

The $sp$ carbon of a terminal alkyne holds its electrons closest, so its hydrogen comes off most readily.

224.White precipitate is formed when _ _ _ _ is passed through ammoniacal solution of silver nitrate. (PMC MDCAT 2022)

  1. Methylene
  2. Ethylene
  3. Acetylene
  4. Vinylene
Show answer

Correct answer: (c) Acetylene

A terminal alkyne is acidic enough to give a white silver acetylide.

225.Benzene is more stable than hypothetical 1,3,5-cyclohexatriene by: (PMC MDCAT 2022)

  1. 150.5 kJ/mol
  2. 150.5J/mol
  3. 150.5 kJ/molecule
  4. 150.5 J/molecule
Show answer

Correct answer: (a) 150.5 kJ/mol

The resonance energy of benzene is about $150\,\mathrm{kJ\,mol^{-1}}$.

226.Benzene is less reactive than its corresponding alkene due to: (PMC MDCAT 2022)

  1. More unsaturation
  2. More saturation
  3. Less electronegativlty difference between C and H atom
  4. Delocalization of π electrons
Show answer

Correct answer: (d) Delocalization of π electrons

The pi electrons are spread over the whole ring, so they are not available as an alkene’s are.

Alkyl Halides

227.Neopentyl chloride belongs to which class of alkyl halides? (MDCAT 2022)

  1. primary alkyl halides
  2. secondary alkyl halides
  3. tertiary alkyl halides
  4. quaternary alkyl halides
Show answer

Correct answer: (a) primary alkyl halides

The carbon carrying the chlorine is attached to only one other carbon, so the halide is primary even though the molecule is branched.

228.2-chlorobutane belongs to: (PMC MDCAT 2022)

  1. Primary Alkyl Halides
  2. Secondary Alkyl Halides
  3. Tertiary Alkyl Halides
  4. Quarternary Alkyl Halides
Show answer

Correct answer: (b) Secondary Alkyl Halides

The chlorine is on carbon 2, which carries two other carbons, so the halide is secondary.

229.The correct name of CH2Cl2 is: (PMC MDCAT 2022)

  1. Methyl chloride
  2. Methylene chloride
  3. Chloroform
  4. Carbonyl chloride
Show answer

Correct answer: (b) Methylene chloride

Dichloromethane is commonly called methylene chloride.

230.Which one of the following is a strong nucleophile? (PMC MDCAT 2022)

  1. Cl-
  2. Br-
  3. OH-
  4. HSO4-
Show answer

Correct answer: (c) OH-

The hydroxide ion carries a full negative charge on a small atom, so it is the strongest nucleophile here.

Alcohols and Phenols

231.What is the common name of 1,2,3-propanetriol? (MDCAT 2022)

  1. butyl alcohol
  2. glycol
  3. glycerol
  4. propyl alcohol
Show answer

Correct answer: (c) glycerol

Three hydroxyl groups on a propane chain make glycerol.

232.Benzene can be formed from phenol in which of the following reactions? (NUMS MDCAT 2022)

  1. Reduction with hydrogen in the presence of Ni
  2. Reduction with zinc
  3. Reduction with alkali
  4. Reduction with acids
Show answer

Correct answer: (b) Reduction with zinc

Distilling phenol with zinc dust takes the oxygen away and leaves benzene.

233.Phenol has following characteristics and physical properties: (NUMS MDCAT 2022)

  1. colorless crystalline solid
  2. colorless crystalline deliquescent solid
  3. Colorless amorphous solid
  4. Colorless amorphous deliquescent solid
Show answer

Correct answer: (b) colorless crystalline deliquescent solid

Phenol is a colourless crystalline solid that takes up water from the air and turns pink on standing.

234.Which of the following reactions are given by alcohol and phenol both? (PMC MDCAT 2022)

  1. Esterification
  2. Nitrosation
  3. Amide formation
  4. Lucas Reaction
Show answer

Correct answer: (a) Esterification

Both the alcohol and the phenol give esters with an acid chloride or anhydride.

235.Lucas test is used for the identification of: (NUMS MDCAT 2022)

  1. Alkyl halides
  2. Alcohols
  3. Alkene
  4. Carboxylic acids
Show answer

Correct answer: (b) Alcohols

Lucas reagent tells primary, secondary and tertiary alcohols apart by how fast each turns cloudy.

Aldehydes and Ketones

236.Which of the following is the correct name of $\mathrm{CH_3CH_2CH_2COCH_2CHO}$? (MDCAT 2022)

  1. 3-oxohexanal
  2. 3-onehexanal
  3. 3-oxohexanone
  4. hexanedial
Show answer

Correct answer: (a) 3-oxohexanal

The aldehyde takes the suffix and is carbon 1, so the ketone at carbon 3 is named as an oxo prefix.

237.Aldehyde common names are derived from carboxylic acid names with the same number of: (PMC MDCAT 2022)

  1. Hydrogen atoms
  2. Carbon atoms
  3. Oxygen atoms
  4. Carbon and hydrogen atoms
Show answer

Correct answer: (b) Carbon atoms

Formaldehyde is named from formic acid, acetaldehyde from acetic acid, and so on.

238.Which of the following is also called the silver mirror test? (MDCAT 2022)

  1. Benedict's solution test
  2. Fehling's solution test
  3. iodoform test
  4. Tollen's reagent test
Show answer

Correct answer: (d) Tollen's reagent test

The aldehyde reduces the silver ion of Tollen's reagent to metallic silver, which plates the tube.

239.AcetaIs are: (PMC MDCAT 2022)

  1. Diethers
  2. Aldehydes
  3. Carboxylic acid
  4. Ketones
Show answer

Correct answer: (a) Diethers

An acetal has two alkoxy groups on the same carbon, so it is a diether.

240.When two moles of acetone are treated with a base, the product is? (PMC MDCAT 2022)

  1. 3-hydroxy-2-methyl pentanone
  2. 4-hydroxy-4 methyl-2-pentanone
  3. 3-hydroxy butanone
  4. 3-hydroxyl pentanal
Show answer

Correct answer: (b) 4-hydroxy-4 methyl-2-pentanone

Base catalysed aldol condensation of two acetone molecules gives diacetone alcohol.

241.Formaldehyde reacts with which one of the following to give primary alcohols (PMC MDCAT 2022)

  1. Fehling's reagent
  2. Benedict's reagent
  3. Grignard's reagant
  4. Millon's reagant
Show answer

Correct answer: (c) Grignard's reagant

A Grignard reagent adds to formaldehyde and the product hydrolyses to a primary alcohol.

242.Aldol products upon heating undergoes: (PMC MDCAT 2022)

  1. Decomposition
  2. Dehydration
  3. Rearrangement
  4. Substitution
Show answer

Correct answer: (b) Dehydration

The aldol loses water on heating and leaves an unsaturated carbonyl compound.

243.lodoform test is used to check the presence of: (PMC MDCAT 2022)

  1. Amines
  2. Carbonyl compounds
  3. Carboxylic acid
  4. Alkyl halides
Show answer

Correct answer: (b) Carbonyl compounds

The iodoform test picks out a methyl ketone or an alcohol that oxidizes to one.

244.The carbanion attacks the molecule of another carbonyl compound to form: (PMC MDCAT 2022)

  1. an alkoxide group
  2. aldol
  3. a carbanion
  4. a carbonium ion
Show answer

Correct answer: (b) aldol

The carbanion adds to the carbonyl carbon of another molecule and the product is an aldol.

245.Fehling’s solution is: (PMC MDCAT 2022)

  1. Alkaline-cupric citrate complex ion
  2. Ammonical AgNO3
  3. Alkaline cupric tartarate complex ion
  4. Sodium nitroprusside solution
Show answer

Correct answer: (c) Alkaline cupric tartarate complex ion

Fehling’s solution is copper(II) held in alkaline solution by tartrate.

246.The identification test for Ketone is: (NUMS MDCAT 2022)

  1. Benedict's Solution Test
  2. Tehling's Solution Test
  3. Sodium Nitro Prusside Test
  4. Town's Test
Show answer

Correct answer: (c) Sodium Nitro Prusside Test

Sodium nitroprusside gives a red colour with a ketone but not with an aldehyde.

247.Acetone is less reactive than acetaldehyde due to: (PMC MDCAT 2022)

  1. More Stearic hindrance offered by its methyl groups.
  2. Electron withdrawing nature of its methyl groups.
  3. Its Carbonyl carbon is sp2 hybridized.
  4. Oxygen of carbonyl group is more electronegative than carbon atom.
Show answer

Correct answer: (a) More Stearic hindrance offered by its methyl groups.

Two methyl groups crowd the carbonyl carbon and push electrons towards it, so it is less open to attack.

Carboxylic Acids

248.When carboxylic acids and dicarboxylic acids have similar molecular weights, how do their melting points compare? (MDCAT 2022)

  1. carboxylic acids have greater melting points
  2. dicarboxylic acids have greater melting points
  3. both acids have similar melting points
  4. there is no consistent pattern
Show answer

Correct answer: (b) dicarboxylic acids have greater melting points

Two carboxyl groups make more hydrogen bonds and pack better, so more heat is needed to break the crystal up.

249.If both carboxylic acid and ketone $\mathrm{C{=}O}$ groups are present in a chain, then the final name will be given as: (MDCAT 2022)

  1. oxo...oic acid
  2. one...oic acid
  3. al...oic acid
  4. none of these
Show answer

Correct answer: (a) oxo...oic acid

The acid outranks the ketone, so the acid takes the suffix and the ketone becomes an oxo prefix.

250.Carboxylic acids are obtained from fats and oils by: (PMC MDCAT 2022)

  1. Oxidation
  2. Reduction
  3. Decarboxylalion
  4. Hydrolysis
Show answer

Correct answer: (d) Hydrolysis

Fats and oils are esters, and hydrolysing them gives glycerol and the fatty acids.

251.Which one of the following carboxylic acid has an unpleasant smell? (PMC MDCAT 2022)

  1. Propionic acid
  2. Formic acid
  3. Butyric acid
  4. Acetic acld
Show answer

Correct answer: (c) Butyric acid

Butyric acid is what gives rancid butter its smell.

252.Acetic acid was first isolated from: (PMC MDCAT 2022)

  1. Ants
  2. Butter
  3. Milk
  4. Vinegar
Show answer

Correct answer: (d) Vinegar

Acetic acid was first got from vinegar, which is where its name comes from.

253.The aliphatic monocarboxylic acids is obtained from (PMC MDCAT 2022)

  1. fats and oils
  2. proteins and oils
  3. fats and proteins
  4. fats only
Show answer

Correct answer: (a) fats and oils

Hydrolysing a fat or an oil gives glycerol and the straight chain fatty acids.

254.Carboxylic acids are water soluble because they: (NUMS MDCAT 2022)

  1. Are more reactive
  2. Have hydrogen bonding
  3. Have low melting point
  4. Have high density
Show answer

Correct answer: (b) Have hydrogen bonding

The carboxyl group hydrogen bonds to water, so the lower members dissolve freely.

255.Which among the following has the least pH? (MDCAT 2022)

  1. $\mathrm{CH_3CH_2COOH}$
  2. $\mathrm{CH_2ClCH_2COOH}$
  3. $\mathrm{CH_3CHClCOOH}$
  4. $\mathrm{CH_3CH_2CH_2COOH}$
Show answer

Correct answer: (c) $\mathrm{CH_3CHClCOOH}$

The chlorine on the carbon next to the carboxyl group pulls electrons away most strongly, so this acid is the strongest and its pH the lowest.

256.Which of the following gas is produced during the reaction of carbonates and bicarbonates with carboxylic acid (PMC MDCAT 2022)

  1. CO2
  2. H2
  3. N2
  4. Ar
Show answer

Correct answer: (a) CO2

A carboxylic acid displaces carbon dioxide from a carbonate or a hydrogen carbonate.

257.Salts of carboxylic acids can be converted into corresponding carboxylic acid by treating with: (PMC MDCAT 2022)

  1. Water
  2. Base
  3. Acid anhydrides
  4. Acid
Show answer

Correct answer: (d) Acid

A stronger acid displaces the weaker carboxylic acid from its salt.

258.The flavour of amyl butyrate is: (PMC MDCAT 2022)

  1. Mango
  2. Raspberry
  3. Apricot
  4. Orange
Show answer

Correct answer: (c) Apricot

Amyl butyrate smells of apricots; the esters are what give fruits their scent.

259.Complete the following reaction: CH3COOC2H5 +H2O —–> (PMC MDCAT 2022)

  1. Both HOC2H5 and CH3CO2H
  2. Both HOCH3 and CH3CO3H
  3. HOC3H6 Only
  4. CH3CO2H Only
Show answer

Correct answer: (a) Both HOC2H5 and CH3CO2H

Hydrolysing the ester gives back the alcohol and the acid.

Macromolecules

260.Which of the following proteins acts as a carrier of copper in blood plasma? (MDCAT 2022)

  1. haemoglobin
  2. glycoprotein
  3. ceruloplasmin
  4. histone
Show answer

Correct answer: (c) ceruloplasmin

Ceruloplasmin carries most of the copper of the plasma.

261.When food reaches the stomach, the action of which enzyme comes to an end because of the acidic pH? (MDCAT 2022)

  1. lipase
  2. amylase
  3. maltase
  4. hydrolases
Show answer

Correct answer: (b) amylase

Salivary amylase works near neutral pH and is denatured by the acid of the stomach.

Other MDCAT past papers