Physical Chemistry MCQs

1. Which of the following is not a state function?

A. Pressure
B. Temperature
C. Internal energy
D. Enthalpy

Answer: A. Pressure

2. The process of conversion of a solid directly into vapor without passing through the liquid state is called:

A. Sublimation
B. Vaporization
C. Melting
D. Condensation

Answer: A. Sublimation

3. Boyle’s law relates:

A. Pressure and temperature
B. Volume and temperature
C. Pressure and volume
D. Volume and moles

Answer: C. Pressure and volume

4. The gas constant R in the ideal gas equation PV = nRT represents:

A. Avogadro’s number
B. Universal gas constant
C. Specific gas constant
D. Boltzmann constant

Answer: B. Universal gas constant

5. Which of the following is an intensive property of a system?

A. Mass
B. Volume
C. Temperature
D. Energy

Answer: C. Temperature

6. The energy associated with the motion of molecules in a substance is:

A. Potential energy
B. Internal energy
C. Kinetic energy
D. Activation energy

Answer: C. Kinetic energy

7. The enthalpy change for a chemical reaction at constant pressure is equal to:

A. q (heat exchange)
B. w (work done)
C. ΔE (change in internal energy)
D. ΔH (change in enthalpy)

Answer: D. ΔH (change in enthalpy)

8. The change in Gibbs free energy (ΔG) of a system at constant temperature and pressure is given by:

A. ΔG = ΔH – TΔS
B. ΔG = ΔH + TΔS
C. ΔG = ΔH / T
D. ΔG = ΔS / T

Answer: A. ΔG = ΔH – TΔS

9. Which statement about catalysts is correct?

A. They change the equilibrium constant of a reaction.
B. They increase the activation energy of a reaction.
C. They are consumed in the reaction.
D. They provide an alternate pathway for the reaction.

Answer: D. They provide an alternate pathway for the reaction.

10. The process of a substance moving from a gas to a solid without passing through the liquid phase is called:

A. Condensation
B. Deposition
C. Sublimation
D. Vaporization

Answer: B. Deposition

11. Which statement about ideal gases is false?

A. Ideal gases have no intermolecular forces.
B. Ideal gases follow the ideal gas law exactly at all conditions.
C. Ideal gases occupy no volume.
D. Ideal gases have elastic collisions.

Answer: B. Ideal gases follow the ideal gas law exactly at all conditions.

12. Which of the following expressions represents the rate of a chemical reaction?

A. Δ[Reactant] / Δt
B. Δ[Product] / Δt
C. Δ[Reactant] / ΔV
D. Δ[Product] / ΔV

Answer: A. Δ[Reactant] / Δt

13. The equilibrium constant (Kc) expression for the reaction aA + bB ⇌ cC + dD is:

A. [C]^c[D]^d / [A]^a[B]^b
B. [A]^a[B]^b / [C]^c[D]^d
C. [C]^c[D]^d – [A]^a[B]^b
D. [A]^a[B]^b + [C]^c[D]^d

Answer: A. [C]^c[D]^d / [A]^a[B]^b

14. An exothermic reaction is one in which:

A. Heat is absorbed from the surroundings.
B. Heat is released to the surroundings.
C. No heat is exchanged with the surroundings.
D. The temperature of the surroundings remains constant.

Answer: B. Heat is released to the surroundings.

15. Which law states that the rate of effusion of a gas is inversely proportional to the square root of its molar mass?

A. Graham’s law
B. Dalton’s law
C. Boyle’s law
D. Charles’s law

Answer: A. Graham’s law

16. The process of removal of electrons from an atom or ion is called:

A. Ionization
B. Reduction
C. Oxidation
D. Discharge

Answer: A. Ionization

17. Which type of bond involves the sharing of electrons between atoms?

A. Ionic bond
B. Covalent bond
C. Metallic bond
D. Hydrogen bond

Answer: B. Covalent bond

18. The pH of a neutral solution at 25°C is approximately:

A. 0
B. 7
C. 14
D. 10

Answer: B. 7

19. Which of the following is a strong acid?

A. HCl
B. CH3COOH
C. H2CO3
D. HCN

Answer: A. HCl

20. The process of conversion of an acid and a base into water and a salt is called:

A. Neutralization
B. Oxidation
C. Reduction
D. Hydrolysis

Answer: A. Neutralization

21. The principle that states that a system at equilibrium will adjust itself to counteract any stress applied to it is known as:

A. Le Chatelier’s principle
B. Boyle’s law
C. Avogadro’s principle
D. Charles’s law

Answer: A. Le Chatelier’s principle

22. Which of the following is a colligative property of a solution?

A. Vapor pressure lowering
B. Boiling point elevation
C. Freezing point depression
D. All of the above

Answer: D. All of the above

23. The energy required to remove an electron from an atom or ion in the gas phase is called:

A. Ionization energy
B. Electron affinity
C. Lattice energy
D. Activation energy

Answer: A. Ionization energy

24. The process in which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water is known as:

A. Efflorescence
B. Hygroscopic
C. Deliquescence
D. Sublimation

Answer: C. Deliquescence

25. The process of conversion of a liquid into vapor at any temperature below its boiling point is called:

A. Evaporation
B. Boiling
C. Condensation
D. Sublimation

Answer: A. Evaporation

26. Which of the following is an intensive property of a substance?

A. Volume
B. Mass
C. Density
D. Heat capacity

Answer: C. Density

27. The specific heat capacity of a substance is defined as the amount of heat required to raise the temperature of:

A. 1 gram of the substance by 1°C
B. 1 mole of the substance by 1°C
C. 1 gram of the substance by 10°C
D. 1 mole of the substance by 10°C

Answer: A. 1 gram of the substance by 1°C

28. Which of the following factors does not affect the rate of a chemical reaction?

A. Temperature
B. Concentration of reactants
C. Surface area of reactants
D. Volume of reactants

Answer: D. Volume of reactants

29. The rate constant of a reaction depends on:

A. Temperature only
B. Concentration of reactants only
C. Nature of reactants only
D. Temperature, concentration of reactants, and nature of reactants

Answer: D. Temperature, concentration of reactants, and nature of reactants

30. Which statement is true regarding an isothermal process?

A. The temperature of the system remains constant.
B. The volume of the system remains constant.
C. The pressure of the system remains constant.
D. The internal energy of the system remains constant.

Answer: A. The temperature of the system remains constant.

31. Which of the following statements is true for an adiabatic process?

A. No heat exchange occurs between the system and the surroundings.
B. The pressure of the system remains constant.
C. The volume of the system remains constant.
D. The temperature of the system remains constant.

Answer: A. No heat exchange occurs between the system and the surroundings.

32. The relationship between the partial pressure of a gas in a mixture and its mole fraction is given by:

A. Dalton’s law
B. Graham’s law
C. Henry’s law
D. Boyle’s law

Answer: A. Dalton’s law

33. Which of the following factors affect the rate of diffusion of a gas?

A. Temperature
B. Molar mass of the gas
C. Pressure
D. All of the above

Answer: D. All of the above

34. The energy associated with the position of particles in a system is called:

A. Kinetic energy
B. Potential energy
C. Internal energy
D. Activation energy

Answer: B. Potential energy

35. Which statement best describes a reversible process in thermodynamics?

A. A process that occurs very slowly with no loss of energy to the surroundings.
B. A process that occurs spontaneously.
C. A process that occurs at constant pressure and temperature.
D. A process that involves a phase change.

Answer: A. A process that occurs very slowly with no loss of energy to the surroundings.

36. The process of dissolving of a gas in a liquid at a particular temperature is described by:

A. Henry’s law
B. Boyle’s law
C. Charles’s law
D. Graham’s law

Answer: A. Henry’s law

37. Which of the following is a non-volatile solute?

A. NaCl
B. Glucose
C. Ethanol
D. Iodine

Answer: B. Glucose

38. The heat capacity of a substance depends on:

A. Its mass only
B. Its volume only
C. Its temperature only
D. Its mass and specific heat capacity

Answer: D. Its mass and specific heat capacity

39. Which of the following is an example of a spontaneous process?

A. Melting ice at -5°C
B. Freezing water at 0°C
C. Boiling water at 100°C
D. Heating a gas in a sealed container

Answer: C. Boiling water at 100°C

40. The process of a solute forming crystals in a solution is called:

A. Dissolution
B. Recrystallization
C. Precipitation
D. Osmosis

Answer: C. Precipitation

41. Which of the following is a state function?

A. Heat
B. Work
C. Enthalpy
D. Energy

Answer: C. Enthalpy

42. Which law states that the pressure of a gas is directly proportional to its absolute temperature, provided that the volume remains constant?

A. Boyle’s law
B. Charles’s law
C. Gay-Lussac’s law
D. Avogadro’s law

Answer: C. Gay-Lussac’s law

43. The ideal gas law can be written as:

A. PV = nRT
B. P = nRT/V
C. PV = RT/n
D. P = RT/nV

Answer: A. PV = nRT

44. Which statement is true regarding an exothermic reaction?

A. The heat content of the system decreases.
B. The heat content of the system increases.
C. The internal energy of the system decreases.
D. The internal energy of the system remains constant.

Answer: B. The heat content of the system increases.

45. The rate of a first-order reaction depends on:

A. The concentration of a single reactant.
B. The concentrations of all reactants.
C. The square of the concentration of a reactant.
D. The cube of the concentration of a reactant.

Answer: A. The concentration of a single reactant.

46. Which of the following is a colligative property of a solution?

A. Viscosity
B. Surface tension
C. Boiling point elevation
D. Refractive index

Answer: C. Boiling point elevation

47. The process of a gas becoming a liquid is called:

A. Evaporation
B. Sublimation
C. Condensation
D. Deposition

Answer: C. Condensation

48. Which of the following is true for an endothermic reaction?

A. Heat is released to the surroundings.
B. The temperature of the surroundings increases.
C. The heat content of the system decreases.
D. The internal energy of the system remains constant.

Answer: B. The temperature of the surroundings increases.

49. Which law states that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the individual gases?

A. Boyle’s law
B. Charles’s law
C. Dalton’s law
D. Gay-Lussac’s law

Answer: C. Dalton’s law

50. The process of conversion of a liquid into vapor at its boiling point is called:

A. Evaporation
B. Sublimation
C. Condensation
D. Vaporization

Answer: D. Vaporization

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