Periodic Properties and Their Trends

Periodic Properties and Their Trends MDCAT MCQs with answers

48 past paper MCQs on Periodic Properties and Their Trends, from the s- and p-Block Elements unit of MDCAT Chemistry. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

Read the notes first Practise the unit as a quiz

1.Which of the following has the highest atomic radius in its period? (MDCAT 2023)

  1. alkaline earth metals
  2. alkali metals
  3. chalcogens
  4. halogens
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Correct answer: (b) alkali metals

The radius falls across a period, so the group I element at the start of each period is the largest.

2.Why does fluorine have less electron affinity as compared to bromine? (MDCAT 2023)

  1. its electronegativity
  2. its small size and dense electronic cloud
  3. seven electrons in its outermost shell
  4. its higher ionization energy
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Correct answer: (b) its small size and dense electronic cloud

The incoming electron is crowded into a very small $2p$ shell, and the repulsion there offsets the attraction of the nucleus.

3.Which of the following has the smallest atomic radius? (MDCAT 2024)

  1. Mg
  2. S
  3. P
  4. Na
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Correct answer: (b) S

Across a period the nuclear charge rises and the radius falls, and sulphur is the furthest right of the four.

4.Which of the following is not basic in nature? (MDCAT 2024)

  1. aluminium oxide
  2. potassium oxide
  3. magnesium oxide
  4. sodium oxide
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Correct answer: (a) aluminium oxide

Aluminium oxide is amphoteric, reacting with acids and with alkalis alike.

5.The element with smallest value of ionization energy is (UHS MDCAT 2025)

  1. Li
  2. Al
  3. Ca
  4. Ba
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Correct answer: (d) Ba

Ionization energy falls down a group, and barium is the lowest of the four.

6.The most electronegative element in periodic table is: (KMU MDCAT 2025)

  1. F
  2. Cl
  3. N
  4. O
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Correct answer: (a) F

Fluorine is the most electronegative of all the elements.

7.Predict the element with lowest ionization energy: (NUMS MDCAT 2025)

  1. Mg
  2. Ar
  3. Si
  4. P
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Correct answer: (a) Mg

Ionization energy rises across a period, and magnesium lies furthest to the left of the four.

8.Select the group II element which has the highest atomic radius? (NUMS MDCAT 2025)

  1. Be
  2. Ca
  3. Ba
  4. Sr
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Correct answer: (c) Ba

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

9.Which of the following element has least boiling point? (NUMS MDCAT 2025)

  1. Li
  2. Na
  3. K
  4. Cs
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Correct answer: (d) Cs

Metallic bonding weakens down group I, so caesium boils lowest.

10.If ionization energy of an element is greater then: (SIBA MDCAT 2025)

  1. More is it's reducing power
  2. More is it's electropositivity
  3. Less is it's metallic character
  4. More is it's atomic radius
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Correct answer: (c) Less is it's metallic character

A high ionization energy means the atom holds its electrons tightly, so it is not metallic.

11.Which of the following has smallest atomic radius (UHS MDCAT 2024)

  1. Mg
  2. S
  3. P
  4. Na
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Correct answer: (b) S

Atomic radius shrinks across a period, and sulphur lies furthest right of the four.

12.The difference of lithium from the other alkall metals is mainly because of: (UHS MDCAT 2024)

  1. Large radius and low charge density
  2. Small radius and low charge density
  3. Large radius and high charge density
  4. Small radius and high charge density
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Correct answer: (d) Small radius and high charge density

The lithium ion is very small and its charge is concentrated, so it polarizes and behaves unlike its group.

13.Which of the following is not Basic in nature (UHS MDCAT 2024)

  1. Aluminum oxide
  2. Magnesium oxide
  3. Potassium oxide
  4. Sodium oxide
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Correct answer: (a) Aluminum oxide

Aluminium oxide is amphoteric; the other three are the basic oxides of group I and II metals.

14.Third period element that initially reacts rapidly with oxygen to form a protective oxide coating that prevents further reactions is (KMU MDCAT 2024)

  1. Al
  2. Ar
  3. Na
  4. Si
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Correct answer: (a) Al

Aluminium takes an oxide film at once, and the film then seals the metal beneath it.

15.In CH3Cl, bond length of C-Cl is 176.7pm and covalent radius of Cl is 99.4pm. Covalent radius of carbon is: (NUMS MDCAT 2024)

  1. 66.3 pm
  2. 276.1 pm
  3. 175.4 pm
  4. 77.3 pm
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Correct answer: (d) 77.3 pm

The bond length is the sum of the two radii, so $176.7-99.4$ leaves $77.3\,\mathrm{pm}$.

16.Correct order of decreasing electron affinities of group VII is: (NUMS MDCAT 2024)

  1. F > Cl > Br > I
  2. Cl > F > Br > I
  3. F < Cl < Br < I
  4. Cl < F < Br < I
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Correct answer: (b) Cl > F > Br > I

Fluorine is so small that the incoming electron is crowded, so chlorine has the greater electron affinity.

17.Q.92 Which of the following element has smaller size? (UHS MDCAT 2023)

  1. Na
  2. K
  3. Al
  4. Li
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Correct answer: (c) Al

Aluminium is furthest to the right in its period of the four, so its atom is the smallest.

18.Q.93 Among LiCl, BeCl2, NaCl, CsCl, the compounds with the greatest and the least ionic character respectively are: (UHS MDCAT 2023)

  1. LiCl and CsCl
  2. NaCl and LiCl
  3. CsCl and NaCl
  4. CsCl and BeCl2
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Correct answer: (d) CsCl and BeCl2

Ionic character grows with the size of the cation and falls with its charge, so caesium chloride is most ionic and beryllium chloride least.

19.Which of the following has greatest difference of electronegativity? (SZABMU MDCAT 2023)

  1. HF
  2. HCl
  3. HBr
  4. HI
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Correct answer: (a) HF

Fluorine is the most electronegative element, so its bond to hydrogen is the most polar.

20.Ionization energy decreases down the group because: (SZABMU MDCAT 2023)

  1. Shielding remains constant
  2. Atomic radius remains constant
  3. Proton number increases
  4. Atomic radius increases
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Correct answer: (d) Atomic radius increases

The outer electron is further from the nucleus and better screened, so it is easier to remove.

21.Which of the following property decreases in Group 2 as we go down the group? (SZABMU MDCAT 2023)

  1. Shielding
  2. Atomic radius
  3. Proton number
  4. Ionization energy
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Correct answer: (d) Ionization energy

The atom grows and its outer electron is easier to pull off, so ionization energy falls.

22.The reason of highest electronegativity value of Fluorine is: (NUMS MDCAT 2023)

  1. Complete outermost shell
  2. Ability to form negative ion
  3. Existence as diatomic molecule
  4. Smaller size and higher nuclear charge in the respective period
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Correct answer: (d) Smaller size and higher nuclear charge in the respective period

Fluorine is the smallest atom of its period with a high nuclear charge, so it pulls hardest on a shared pair.

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

  1. Cations
  2. Anions
  3. Radicals
  4. Free radicals
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Correct answer: (a) Cations

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

24.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
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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.

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

  1. 37.7 pm
  2. 37.7 nm
  3. 37.7 mm
  4. 37.7μm
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Correct answer: (a) 37.7 pm

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

26.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
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Correct answer: (d) Remain unchanged

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

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

  1. Li
  2. Na
  3. K
  4. Rb
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Correct answer: (d) Rb

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

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

  1. Be
  2. Mg
  3. Ca
  4. Ba
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Correct answer: (d) Ba

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

29.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
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Correct answer: (a) Rb

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

30.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
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Correct answer: (c) Any Two

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

31.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
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Correct answer: (a) Hydration energy

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

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

  1. Proton number increases
  2. Atomic radius increases
  3. Shielding decrease
  4. Rate constant
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Correct answer: (b) Atomic radius increases

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

33.Which ion will have a maximum value of the heat of hydration? (PMC Practice 2021)

  1. Al+3
  2. Cs+
  3. Ba+
  4. Mg+2
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Correct answer: (a) Al+3

Hydration energy rises with the charge and falls with the size, and the aluminium ion is small and triply charged.

34.The ionization energy increases from left to right in a period due to increase in? (PMC Practice 2021)

  1. Nuclear charge
  2. Number of electrons
  3. Atomic number
  4. All of these
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Correct answer: (a) Nuclear charge

The nuclear charge grows across a period while the shell stays the same, so the electrons are held more tightly.

35.By increasing which of the following factor polarizability increases? (PMC Practice 2021)

  1. Atomic radius
  2. Ionization energy
  3. Ionic radius
  4. Hydration energy
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Correct answer: (a) Atomic radius

A larger atom holds its outer electrons loosely, so its cloud is the more easily distorted.

36.Covalent character of hydrides decrease ________? (PMC Practice 2021)

  1. Down the Group
  2. Along period
  3. Along d- block
  4. All of these
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Correct answer: (a) Down the Group

The bond grows more ionic as the element gets larger and less electronegative.

37.Boiling point of hydrides of the 4th period is larger than __________. (PMC Practice 2021)

  1. 5th period
  2. 3rd period
  3. 6th period
  4. 7th period
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Correct answer: (b) 3rd period

The molecules are larger and their dispersion forces stronger, so the hydrides boil higher.

38.The increase in size of an anion is due to the increase in repulsion of: (PMC Practice 2021)

  1. Electron-proton
  2. Electron-electron
  3. Electron-nucleus
  4. Proton-nucleus
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Correct answer: (b) Electron-electron

An anion has more electrons than protons, so they repel each other more and the cloud spreads.

39.The unit of electronegativity is? (PMC Practice 2021)

  1. Joule
  2. Kilojoules
  3. Watt
  4. No unit
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Correct answer: (d) No unit

Electronegativity is a relative number on an arbitrary scale, so it has no unit.

40.Which of the following has the highest value of electronegativity? (PMC MDCAT 2020)

  1. I
  2. Br
  3. Cl
  4. F
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Correct answer: (d) F

Fluorine is the most electronegative element.

41.Densities of alkali metals are low due to: (PMC MDCAT 2020)

  1. Weak intermolecular forces
  2. Large atomic volume
  3. Smaller size
  4. Ns1 configuration
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Correct answer: (b) Large atomic volume

The atoms are large and loosely packed, so a given mass takes up a great deal of room.

42.The first ionization energy is maximum for: (PMC MDCAT 2020)

  1. Na
  2. Mg
  3. Al
  4. K
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Correct answer: (b) Mg

Magnesium has a filled 3s subshell, which makes its first electron harder to remove than aluminium’s.

43.In the second period of elements, although oxygen lies next to nitrogen yet its ionization first energy is lower than that of nitrogen because? (UHS MDCAT 2019)

  1. Oxygen is paramagnetic in character
  2. Nuclear charger of oxygen is greater than nitrogen
  3. Oxygen has higher electron affinity
  4. In oxygen, there exists repulsion between pair of electrons present in the same orbital of valence shell.
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Correct answer: (d) In oxygen, there exists repulsion between pair of electrons present in the same orbital of valence shell.

Nitrogen has a half filled p subshell; in oxygen one orbital holds a pair, and their repulsion makes that electron easier to remove.

44.Ionization energy decreases down the group, from top to bottom, due to: (UHS MDCAT 2019)

  1. Increase in atomic mass
  2. Increase in shielding effect of the intervening electrons
  3. Increase in proton number
  4. Decrease in atomic size
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Correct answer: (b) Increase in shielding effect of the intervening electrons

More inner shells screen the outer electron better, so it is easier to remove.

45.Electron affinity of the atom is the energy released when: (UHS MDCAT 2018)

  1. Covalent bond of molecule is broken
  2. Electron is added to gaseous atom
  3. Electron is removed from gaseous atom
  4. Covalent bond is formed between the atoms
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Correct answer: (b) Electron is added to gaseous atom

Electron affinity is the energy given out when an electron is added to a gaseous atom.

46.In Period 2 and Period 3 maximum melting point shown by elements: (UHS MDCAT 2018)

  1. Nitrogen and Phosphorus
  2. Neon and Argon
  3. Lithium and Sodium
  4. Carbon and Silicon
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Correct answer: (d) Carbon and Silicon

Carbon and silicon are covalent networks bonded right through, so they melt highest in their periods.

47.Ionic radius decreases along the period due to: (UHS MDCAT 2017)

  1. Addition of a new shell
  2. Increase in nuclear charge
  3. High Ionization Energy
  4. Decrease in nuclear charge
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Correct answer: (b) Increase in nuclear charge

The nuclear charge grows across a period while the shell stays the same, so the ions shrink.

48.The ionic radius of fluoride ion is: (UHS MDCAT 2016)

  1. 72 pm
  2. 95 pm
  3. 136 pm
  4. 157 pm
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Correct answer: (c) 136 pm

The fluoride ion is much larger than the atom, about $136\,\mathrm{pm}$.

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