# MCQ Questions for Class 11 Chemistry Chapter 6 Thermodynamics with Answers

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## Thermodynamics Class 11 MCQs Questions with Answers

Multiple Choice Type Questions

Question 1.
One gram of sample of NH4NO3 is decomposed in a bomb calorimeter. The temperature of the calorimeter increases by 6.12 K. The heat capacity of the system is 1.23 kj/deg. What is the molar heat of decomposition of NH4NO3?
(a) -7.53 kj/mol
(b) -398.1 kj mol-1
(c) -16.1 kj/mol
(d) -602 kj/mol.

Question 2.
AHr of graphite is 0.23 kj/mol and ∆Hf for diamond is 1.896 kj mol-1, ∆Htransition from graphite to diamond is
(a) 1.66 kj/mol
(b) 2.1 kj/mol
(c) 2.33 kj/mol
(d) 1.5 kj/mol

Question 3.
The bond energies of C-C, C=C; H-H and C-H linkages are 350, 600, 400 and 410 kj per mole respectively. The heat of hydrogenation of ethylene is
(a) -170 kj mol-1
(b) -260 kj mol-1
(c) 400 kj mol-1
(d) -450 kj mol-1

Question 4.
Which of the following reaction defines ∆H$$_{f}^{0}$$?
(a) C(Diamond) + O2(g) → CO2(g)
(b) $$\frac {1}{2}$$ H2(g) + $$\frac {1}{2}$$ F2(g) → HF(g)
(c) N2(g) + 3H2(g) → 2NH3(g)
(d) CO(g) + $$\frac {1}{2}$$ O2(g) → CO2(g)

Answer: (b) $$\frac {1}{2}$$ H2(g) + $$\frac {1}{2}$$ F2(g) → HF(g)

Question 5.
One mole of a hon-ideal gas undergoes a change of state (2.0 atm, 3.0 L, 95 K) → (4.0 atm, 5.0 L, 245 K) with a change in internal energy, ∆U = 30.0 L atm. The change in enthalpy (∆H) of the process in L atm is
(a) 44.0
(b) 42.3
(c) 44.0
(d) not defined because pressure is not constant.

Question 6.
Which one of the following statement is false?
(a) Work is a state function
(b) Temperature is a state function
(c) Change in the state is completely defined when the initial final states are specified
(d) Work appears at the boundary of the system

Answer: (a) Work is a state function

Question 7.
Molar heat capacity of water in equilibrium with ice at constant pressure is
(a) zero
(b) infinity
(c) 40.45 kj K-1 mol-1
(d) 75.48 JK-1 mol-1

Question 8.
For the reaction C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(I) at constant temperature ∆H – ∆E is
(a) + RT
(b) – 3RT
(c) + 3RT
(d) -RT

Question 9.
For which one of the following equations AHreaction equals ∆H$$_{f}^{0}$$ for the product?
(a) N2(g) + O3(g) → N2O3(g)
(b) CH4(g) + 2Cl2(g) → CH2Cl2(l) + 2HCl(g)
(c) Xe(g) + 2F2(g) → XeF4(g)
(d) 2C(g) + O2(g) → 2CO2(g)

Answer: (c) Xe(g) + 2F2(g) → XeF4(g)

Question 10.
Enthalpy of CH4 + $$\frac {1}{2}$$ O2 → CH3OH is negative.
If enthalpy of combustion of CH4 and CH3OH are x and y respectively then which reaction is correct?
(a) x > y
(b) x < y
(c) x = y
(d) x ≥ y

Question 11.
The heat required to raise the temperature of a body by 1 K is called
(a) Specific heat
(b) Thermal capacity
(c) Water equivalent
(d) Molar heat capacity

Question 12.
In a reaction involving only solids and liquids, which of the following is true?
(a) ∆H < ∆E (b) ∆H = ∆E (c) ∆H > ∆E
(d) ∆H = ∆E + RT∆11

Question 13.
In which of the following process, the process is always non-feasible?
(a) ∆H > 0, ∆S > 0
(b) ∆H < 0, ∆S > 0
(c) ∆H > 0, ∆S < 0
(d) ∆H < 0, ∆S < 0

Answer: (c) ∆H > 0, ∆S < 0

Question 14.
Internal energy does not include
(a) Nuclear energy
(b) Vibrational energy
(c) Rotational energy
(d) Energy of gravitational pull

Answer: (d) Energy of gravitational pull

Question 15.
Which of the following reactions is endothermic?
(a) N2 + O2 → 2NO
(b) H2 + Cl2 → 2HCl
(c) H2SO4 + 2NaOH → Na2SO4 + 2H11O
(d) None of these

Answer: (a) N2 + O2 → 2NO

Question 16.
An adiabatic’expansion of an ideal gas always has
(a) Decrease in temperature
(b) q = 0
(c) W = 0
(d) ∆H = 0.

Question 17.
Amount of heat required to change 1 g ice at 0°C to 1 g steam at 100°C is
(a) 616 cal
(b) 12 R cal
(c) 717 cal
(d) None of these

Question 18.
In what proportional 1 M NaOH and 0.5 MH2SO4 are mixed respectively so as to release maximum amount of energy and to form 100 ml of solution?
(a) 33 and 67
(b) 67 and 33
(c) 40 and 60
(d) 50 and 50

Question 19.
In order to decompose 9 g water, 142.5 kj heat is required. Hence the enthalpy of formation of water is
(a) -196 kj mol-1
(b) +196 kj mol-1
(c) +948 kj mol-1
(d) -948 kj mol-1

Question 20.
Change in enthalpy for the reaction 2H2O2(l) → 2H2O(l) + O2(g) if the heat of formation of H2O2(l) and H2O(l) are – 188 kj mol-1 and -283 kj mol-1. Therefore the heat of formation of CO in kj mol-1 is
(a) +172.5
(b) -110.5
(c) -1070
(d) -676.5
(e) +110.5

Question 21.
The heats of combustion of graphite and CO respectively are -393.5 kj mol-1 and -283 kj mol-1. Therefore the heat of formation of CO in kj moj-1 is.
(a) +172.5
(b) -110.5
(c) -1070
(d) -676.5
(e) +110.5

Question 22.
Compounds with high heat of formation are less stable because
(a) It is difficult to synthesise them
(b) Energy rich state leads to instability
(c) High temperature is required to synthesise them
(d) Molecules of such compounds are distorted

Question 23.
C(diamond) → C(graphite) ∆H = -ve. This shows that
(a) Graphite is more stable than diamond
(b) Diamond is more stable than graphite
(c) Both are equally stable
(d) Stability cannot be predicted.

Answer: (a) Graphite is more stable than diamond

Question 24.
Enthalpy of neutralisation of HCl with NaOH is x. The heat evolved when 500 ml of 2N HCl are mixed with 250 ml of 4N NaOH will be
(a) 500x
(b) 100x
(c) x
(d) 10x

Question 25.
In a closed insulated container, a liquid is stirred with a paddle to increase the temperature. Which of the following is true?
(a) ∆E = W ≠ 0, q = 0
(b) ∆E = W = q ≠ 0
(c) ∆E = 0, W = q ≠ 0
(d) W = 0, ∆E = q ≠ 0

Answer: (a) ∆E = W ≠ 0, q = 0

Question 26.
For an endothermic reaction ∆S is positive, the reaction is
(a) feasible when T∆S > ∆H
(b) feasible when ∆H > T∆S
(c) feasible at all temperature
(d) Not feasible at all

Answer: (a) feasible when T∆S > ∆H

Question 27.
In thermodynamics a process is called reversible when
(a) Surroundings and system change into each other
(b) There is no boundary between system and surroundings
(c) The surroundings are always in equilibrium with the system
(d) The system changes into surroundings spontaneously

Answer: (c) The surroundings are always in equilibrium with the system

Question 28.
Entropy change involved in the conversion of 1 mol of liquid water at 373 K to vapour at the same temperature will be (∆Hvap = 2.257 kJg-1)
(a) 0.119 kj
(b) 0.109 kj
(c) 0.129 kj
(d) 0.120 kj

Question 29.
2 mol of an ideal gas at 27°C is expanded reversibly from 2 L to 20 L. Find entropy change (R = 2 cal/mol K) in cal K-1 mol-1
(a) 92.1
(b) 0
(c) 4
(d) 9.2

Question 30.
Which of the following is not a state function
(a) ∆G
(b) ∆E
(c) W
(d) H

Question 31.
For the reaction H2(s) ⇌ H2O(l) at 0°C and normal pressure
(a) ∆H < T∆S
(b) ∆H = ∆G
(c) EH = T∆S
(d) ∆H > T∆S

Question 32.
Which of the following does not result in an increase in entropy?
(a) Crystallisation of surcose from solution
(b) Rusting of iron
(c) Conversion of ice to water
(d) Vaporisation of camphor

Answer: (a) Crystallisation of surcose from solution

Question 33.
The unit of entropy is
(a) joule
(b) joule per mole
(c) joule per Kelvin
(d) joule per gram.

Question 34.
In the reaction normal egg → Hard boiled egg ∆S is
(a) -ve
(b) 0
(c) +ve
(d) +ve and 0.

Question 35.
PbO2 → PbO, ∆G298 < 0
SnO2 → SnO, ∆G298 > 0.
Most probable oxidation state of Pb and Sn will be
(a) Pb+4, Sn+4
(b) Pb+4, Sn-2
(c) Pb+2, Sn+2
(d) Pb+2, Sn+4

Question 36.
The bond dissociation energies for Cl2, I2 and ICl are 242.3, 151.0 and 211.3 kj mol-1 respectively. The enthalpy of sublimation of iodine is 62.8 kj mol-1 What is the standard1 enthalpy of formation of ICl(g) nearly equal to
(a) -211.3 kj mol-1
(b) -14.6 kj mol-1
(c) 16.8 kj mol-1
(d) 33.5 kj mol-1

Question 37.
The quantity of heat measured for a reaction in a bomb calorimeter is equal to
(a) ∆G
(b) ∆H
(c) P∆V
(d) ∆E

Question 38.
Consider the following reactions:
(i) H+(aq) + OH(aq) → H2O(l); ∆H = – X1kJ mol-1
(ii) H2(g) + $$\frac {1}{2}$$ O2(g) → H2O(l); ∆H = – X2 kj mol-1
(iii) CO2(g) + H2(g) → CO(g) + HO(l) – X3kJ mol-1
(iv) C2H2(g) + $$\frac {1}{2}$$ O2(g) → 2CO2(g) + H2O(l) + X4 kj mol-1
Enthalpy of formation of H2O(l) is
(a) +X1 kj mol-1
(b) -X2 kj mol-1
(c) +X3 kj mol-1
(d) -X4 kj mol-1

Question 39.
Given that the bond energies of H-H and Cl-Cl are 430 kj mol-1 and 240 kj mol-1 respectively and ∆fH for HCl is – 90 kj mol-1 Bond enthalpy of HCl is
(a) 245 kj mol-1
(b) 290 kj mol-1
(c) 380 kj mol-1
(d) 425 kj mol-1.

Question 40.
If K < 1.0, what will be the value of ∆G° of the following?
(a) 1.0
(b) zero
(c) Negative
(d) Positive

Fill in the Blanks

Question 1.
In a closed system, there is no exchange of ……………… but exchange of ……………… is possible between the system and the surroundings.

Question 2.
When there is no exchange of heat taking place between the system and surroundings, it is said to undergo ……………… process.

Question 3.
The state function is one whose value depends on ……………… state and ……………… state of the system and not on the ……………… followed.

Question 4.
The positive sign of w indicates work done …………….. the system and negative sign of w indicates work done ……………… the system.

Question 5.
I law of thermodynamics states that energy of an isolated system is ………………

Question 6.
Mathematically 1 law of thermodynamics is q + w = ………………

Question 7.
∆H is ……………… for exothermic reactions and ∆H is ……………… for endothermic reactions.

Question 8.
Internal energy is an ……………… property and pressure is ……………… property.

Question 9.
The experimental techniques to measure energy changes associated with chemical and physical processes is called ………………

Question 10.
Lattice energy of an ionic compound like Na+Cl can be calculated using ………………

True/False Statements

Question 1.
q is positive when heat is transferred from the surroundings to the system.

Question 2.
∆H indicates change in energy at constant volume.

Question 3.
Work is a state function.

Question 4.
Enthalpy is the total heat content of a system at constant pressure.

Question 5.
The standard state of a substance at a specified temperature is the pure form at 1 bar.

Question 6.
If ∆G > 0, the process is spontaneous.

Question 7.
A spontaneous process is an irreversible process.

Question 8.
Entropy is the measure of orderliness of a system.

Question 9.
A process in which ∆H is positive and ∆S is negative is spontaneous.

Question 10.
Many reactions which are non-spontaneous at low temperature, are made spontaneous at high temperatures having positive entropy.

Match Type Questions

 Column I Column II 1. Internal energy (i) U + PV 2. Enthalpy H (ii) ∫PdV 3. Work of an expansion contractions (iii) $$\frac {q_{rev}}{T}$$ 4. ∆S (iv) State function

 Column I Column II 1. Internal energy (iv) State function 2. Enthalpy H (i) U + PV 3. Work of an expansion contractions (ii) ∫PdV 4. ∆S (iii) $$\frac {q_{rev}}{T}$$

 Column I Column II 1. ∆G (i) Rln ($$\frac {V_2}{V_1}$$) 2. ∆ST (ii) RTln ($$\frac {V_1}{V_2}$$) 3. ∆U (iii) CvdT 4. wadiabatic (iv) (∆H)v – V∆P

 Column I Column II 1. ∆G (ii) RTln ($$\frac {V_1}{V_2}$$) 2. ∆ST (i) Rln ($$\frac {V_2}{V_1}$$) 3. ∆U (iii) CvdT 4. wadiabatic (iv) (∆H)v – V∆P

 Column I Column II 1. Isothermal process (i) q = ∆U 2. Adiabatic process (ii) w = – P∆V 3. Isobaric process (iii) w = ∆U 4. Isochoric process (iv) w = nRTln ($$\frac {V_2}{V_1}$$)

 Column I Column II 1. Isothermal process (iv) w = nRTln ($$\frac {V_2}{V_1}$$) 2. Adiabatic process (iii) w = ∆U 3. Isobaric process (ii) w = – P∆V 4. Isochoric process (i) q = ∆U

 Column I Column II 1. Pressure (i) Intensive property 2. Entropy (ii) Extensive property 3. Work (iii) State function 4. Enthalpy (iv) Path function