Multiple Choice Questions and Answers on Class 11 Chemistry Chapter 6 Thermodynamics

1 Standard enthalpy of vapourisation ΔHvap for water at 100oC is 40.66 kJmol-1. The internal energy of vapourisation of water at 100°C (in kJmol-1) is (Assume water vapour to behave like an ideal gas)

A 43.76

B 40.66

C 37.56

D -43.76

View Answer

Answer:37.56

2 Which of the following salts will have maximum cooling effect when 0.5 mole of the salt is dissolved in same amount of water. Integral heat of solution at 298 K is given for each salt?

A KNO₃ (∆H = 35.4 kJ mol^-1)

B NaCl (∆H = 5.35 kJ mol^-1)

C HBr (∆H = -83.3 kJ mol^-1)

D KOH ( ∆H = -55.6 kJ mol^-1)

View Answer

Answer:KNO₃ (∆H = 35.4 kJ mol^-1)

3 The temperature of the system decreases in an ______.

A Adiabatic Compression

B Isothermal Expansion

C Isothermal Compression

D Adiabatic Expansion

View Answer

Answer:Adiabatic Expansion

4 A system absorb 10 kJ of heat at constant volume and its temperature rises from 270°C to 370°C. The value of ∆ U is

A 100 kJ

B 10 kJ

C 0 kJ

D 1 kJ

View Answer

Answer:10 kJ

5 Based on the first law of thermodynamics, which one of the following is correct?

A For an isothermal process, q = +w

B For an isochoric process, ΔU = -q

C For an adiabatic process, ΔU = -w

D For a cyclic process, q = -w

View Answer

Answer:For a cyclic process, q = -w

6 The amount of the heat released when 20 ml 0.5 M NaOH is mixed with 100 ml 0.1 M HCl is x kJ. The heat of neutralization is

A -100 × kJ/mol

B -50 × kJ/mol

C 100 × KJ/mol

D 50 × kJ/mol

View Answer

Answer:-100 × kJ/mol

7 The enthalpies of combustion of carbon and carbon monoxide are -393.5 and -283.0 kJ mol^-1 respectively. The enthalpy of formation of carbon monoxide is:

A -676 kJ

B 110.5 kJ

C -110.5 kJ

D 676.5 kJ

View Answer

Answer:-110.5 kJ

8 Which thermodynamic function accounts automatically for enthalpy and entropy both?

A Helmholtz Free Energy (A)

B Internal Energy (E)

C Work Function

D Gibbs Free Energy

View Answer

Answer:Gibbs Free Energy

9 The bond energy (in kcal mol^-1) of a C-C single bond is approximately

A 1

B 10

C 83-85

D 1000

View Answer

Answer:83-85

10 In which of the following process, a maximum increase in entropy is observed?

A Dissolution of Salt in Water

B Condensation of Water

C Sublimation of Naphthalene

D Melting of Ice

View Answer

Answer:Sublimation of Naphthalene

11 An ideal gas is taken around the cycle ABCA as shown in P-V diagram The next work done by the gas during the cycle is equal to:

thermodynamics

A 12P₁V₁

B 6P₁V₁

C 5P₁V₁

D P₁V₁

View Answer

Answer:5P₁V₁

12 A system absorb 10 kJ of heat at constant volume and its temperature rises from 270 C to 370 C. The value of ∆ U is

A 100 kJ

B 10 kJ

C 0 kJ

D 1 kJ

View Answer

Answer:10 kJ

13 In a system where ∆E = -51.0 kJ, a piston expanded against a p_ext of 1.2 atm giving a change in volume of 32.0 L. What was the change in heat of this system?

A -36 kJ

B -13 kJ

C -47 kJ

D 24 kJ

View Answer

Answer:-47 kJ

14 Calculate the heat required to make 6.4 Kg CaC₂ from CaO(s) and C(s) from the reaction: CaO(s) + 3 C(s) → CaC₂(s) + CO (g) given that ∆_f Ho (CaC₂) = -14.2 kcal. ∆_f H° (CO) = -26.4 kcal.

A 5624 kcal

B 1.11 × 10⁴ kcal

C 86.24 × 10³

D 1100 kcal

View Answer

Answer:1.11 × 10⁴ kcal

15 Which of the following is true for the reaction? H₂O (l) ↔ H₂O (g) at 100° C and 1 atm pressure

A ∆S = 0

B ∆H = T ∆S

C ∆H = ∆U

D ∆H = 0

View Answer

Answer:∆S = 0

16 In a reversible process the system absorbs 600 kJ heat and performs 250 kJ work on the surroundings. What is the increase in the internal energy of the system?

A 850 kJ

B 600 kJ

C 350 kJ

D 250 kJ

View Answer