Properties of Liquids

Properties of Liquids MDCAT MCQs with answers

16 past paper MCQs on Properties of Liquids, from the Liquids 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 type of forces exist between iodine molecules? (MDCAT 2023)

  1. dipole-dipole forces
  2. dipole-induced dipole forces
  3. instantaneous dipole-induced dipole forces
  4. hydrogen bonding
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Correct answer: (c) instantaneous dipole-induced dipole forces

Iodine is non-polar, so only London dispersion forces hold its molecules together.

2.Which of the following is responsible for the low boiling point of diethyl ether as compared to water? (NUMS MDCAT 2025)

  1. Weak intermolecular forces
  2. High surface tension
  3. Low vapour pressure
  4. High vapour pressure
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Correct answer: (a) Weak intermolecular forces

Ether molecules attract each other only by weak dipole forces, while water is held by hydrogen bonds.

3.The weakest intermolecular force present in liquid is? (SZABMU MDCAT 2025)

  1. dipole dipole forces
  2. induce dipole force
  3. Instantaneous dipole induced dipole force
  4. hydrogen bonding
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Correct answer: (c) Instantaneous dipole induced dipole force

London forces between instantaneous dipoles are the weakest of the intermolecular attractions.

4.The maximum polarizability is exhibited in: (NUMS MDCAT 2024)

  1. C6H14
  2. C3H6
  3. C5H12
  4. C2H6
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Correct answer: (a) C6H14

The largest, most loosely held electron cloud is the most easily distorted, and hexane is the biggest here.

5.In liquid, with the change in dipole-dipole forces, there is a change in some physical properties. Select the property which is not affected by the strength of dipole-dipole forces? (UHS MDCAT 2023)

  1. boiling point
  2. heat of vaporization
  3. heat of sublimation
  4. moles
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Correct answer: (d) moles

The number of moles is fixed by how much substance there is, not by the forces between its molecules.

6.Which of the following has highest surface tension? (SZABMU MDCAT 2023)

  1. Benzene
  2. Alcohols
  3. Ether
  4. Water
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Correct answer: (d) Water

Water is held by hydrogen bonds, which gives it much the greatest surface tension of these.

7.Which of the following has highest boiling point? (SZABMU MDCAT 2023)

  1. C4H10
  2. C6H14
  3. C10H22
  4. C2H6
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Correct answer: (c) C10H22

The longest chain has the largest surface for its dispersion forces, so decane boils highest.

8.The boiling point of ether is less as compared to alcohols and phenols due to: (NUMS MDCAT 2023)

  1. Functional group
  2. Intermolecular forces
  3. Nature of alkyl groups
  4. Isomerism
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Correct answer: (b) Intermolecular forces

An ether has no hydroxyl hydrogen, so it cannot hydrogen bond as an alcohol or a phenol does.

9.Which is not a property of liquid? (UHS MDCAT 2023)

  1. Osmotic pressure
  2. Freezing point
  3. Diffusion
  4. Melting
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Correct answer: (d) Melting

Melting is what a solid does; a liquid boils or freezes.

10.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
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Correct answer: (a) 4.18 J/g/°C

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

11.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
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Correct answer: (c) Water molecule is polar

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

12.Instantaneous dipole is produced when ________. (PMC Practice 2021)

  1. Two polar molecules come closer
  2. Two non-polar molecules comes closer
  3. Polar and non-polar molecule comes closer
  4. All of these options are correct
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Correct answer: (b) Two non-polar molecules comes closer

The electron cloud of one non-polar molecule is momentarily lopsided and induces the same in its neighbour.

13.Water is considered as a universal solvent because of which properties? (PMC Practice 2021)

  1. Polar nature of water
  2. H-bonding
  3. Electronegativity difference
  4. All of these options are correct
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Correct answer: (d) All of these options are correct

Water is polar, hydrogen bonds and has a large electronegativity difference, so it dissolves ionic and polar substances alike.

14.Which of the following forces have no relation with valence electrons? (PMC Practice 2021)

  1. Ionic Bond
  2. Chemical bond
  3. Intermolecular forces
  4. Intramolecular forces
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Correct answer: (c) Intermolecular forces

Intermolecular forces act between whole molecules; it is the valence electrons that make the bonds inside them.

15.CO2 and SO2 both are tri-atomic molecules but heat of vaporization of SO2 is greater than that of CO2 due to: (PMC MDCAT 2020)

  1. High electronegativity of S
  2. Greater size of SO2
  3. SO2 is polar and CO2 is non-polar
  4. SO2 is more acidic than CO2
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Correct answer: (c) SO2 is polar and CO2 is non-polar

Sulphur dioxide is bent and polar, so its molecules attract each other far more strongly.

16.London dispersion forces are the only forces present among the ____. (UHS MDCAT 2016)

  1. Molecules of H2O in liquid state
  2. Molecules of HCl gas
  3. Atoms of helium in gaseous state at high temperature
  4. Molecules of solid chlorine
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Correct answer: (d) Molecules of solid chlorine

Chlorine is non-polar, so only instantaneous dipoles hold its molecules in the solid.

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