NEET UG CHEMISTRY Multiple Choice Questions (MCQs)

46. Which of the following is an example of an intensive property?

a) Mass

b) Volume

c) Temperature

d) Energy

Answer: c) Temperature

47. The change in internal energy (ΔU) of a system is equal to:

a) Heat absorbed by the system at constant pressure

b) Heat absorbed by the system at constant volume

c) Work done by the system

d) Work done on the system

Answer: b) Heat absorbed by the system at constant volume

48. Which of the following statements is correct according to the first law of thermodynamics?

a) Heat is a state function

b) ΔU = q + w

c) Enthalpy is always positive

d) Work done is independent of the path

Answer: b) ΔU = q + w

49. What is the SI unit of work in thermodynamics?

a) Calorie

b) Joule

c) Watt

d) Atmosphere

Answer: b) Joule

50. The enthalpy change (ΔH) during the process of combustion of a substance is:

a) Equal to the change in internal energy

b) The heat absorbed at constant volume

c) The heat released at constant pressure

d) The change in energy at constant pressure

Answer: c) The heat released at constant pressure

51. Hess's law of constant heat summation is based on the principle of:

a) Conservation of energy

b) Conservation of mass

c) Reversible processes

d) Irreversible processes

Answer: a) Conservation of energy

52. The enthalpy of formation of a compound is the heat change when:

a) One mole of the substance is burned completely

b) One mole of a substance is formed from its elements in their standard states

c) One mole of a substance undergoes sublimation

d) One mole of a substance dissolves in water

Answer: b) One mole of a substance is formed from its elements in their standard states

53. The standard enthalpy of atomization refers to:

a) The enthalpy change when one mole of a compound is formed from its elements in their standard states

b) The enthalpy change when one mole of a substance is converted into individual atoms

c) The heat released during the formation of a bond

d) The heat absorbed during the formation of a compound

Answer: b) The enthalpy change when one mole of a substance is converted into individual atoms

54. In the second law of thermodynamics, spontaneity of a process depends on:

a) The change in internal energy of the system

b) The change in entropy of the system only

c) The change in entropy of the universe

d) The enthalpy change of the surroundings

Answer: c) The change in entropy of the universe

55. The spontaneity of a process is determined by the change in:

a) Enthalpy (ΔH)

b) Internal energy (ΔU)

c) Gibbs free energy (ΔG)

d) Heat (q)

Answer: c) Gibbs free energy (ΔG)

56. Which of the following processes is always spontaneous at low temperature?

a) Melting of ice

b) Sublimation of dry ice

c) Dissolution of NaCl in water

d) Freezing of water

Answer: d) Freezing of water

57. The standard Gibbs free energy change (ΔG°) for a reaction at equilibrium is:

a) Zero

b) Negative

c) Positive

d) Undefined

Answer: a) Zero

58. If ΔG° for a reaction is negative, the reaction is:

a) Non-spontaneous

b) At equilibrium

c) Spontaneous

d) Undefined

Answer: c) Spontaneous

59. The relationship between the Gibbs free energy change (ΔG°) and the equilibrium constant (K) is given by:

a) ΔG° = -RT ln K

b) ΔG° = RT ln K

c) ΔG° = -RT ln (1/K)

d) ΔG° = K ln R

Answer: a) ΔG° = -RT ln K

60. Which of the following enthalpies is related to the heat released or absorbed when one mole of a substance dissolves in water?

a) Enthalpy of formation

b) Enthalpy of combustion

c) Enthalpy of solution

d) Enthalpy of atomization

Answer: c) Enthalpy of solution