Question Set A

CBSE 11th Chemistry Chemical Thermodynamics Model Questions Papers Study Material - QB365

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Questions:

Multiple Choice Question

50 x 1 = 50

For which of the following processes ΔS is negative ______.

(a)

\(\mathrm{H}_{2}(g) \longrightarrow 2 \mathrm{H}(g)\)

(b)

\(\mathrm{N}_{2}(g, 1 \mathrm{~atm}) \longrightarrow \mathrm{N}_{2}(g, 5 \mathrm{~atm})\)

(c)

\(2 \mathrm{SO}_{3}(g) \longrightarrow 2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g)\)

(d)

\(\mathrm{C}(\text { diamond }) \longrightarrow \mathrm{C}(\text { graphite })\)

Consider the reactions given below. On the basis of these reactions find out which of the algebric relations given in options (a) to (d) is correct?
(i) \( \mathrm{C}(g)+4 \mathrm{H}(g) \longrightarrow \mathrm{CH}_{4}(g) ; \Delta_{r} H=x \mathrm{~kJ} \mathrm{~mol}^{-1} \)
(ii)\( \text { C(graphite, } s)+2 \mathrm{H}_{2}(g) \longrightarrow \mathrm{CH}_{4}(g) ; \Delta_{r} H \doteq y \mathrm{~kJ} \mathrm{~mol}^{-1} \)

(a)

x = y

(b)

x = 2y

(c)

x > y

(d)

x < y

Which of the following statements is correct?

(a)

The presence of reacting species in a covered beaker is an example of open system.

(b)

There is an exchange of energy as well as matter between the system and the surroundings in a closed system.

(c)

The presence of reactants in a closed vessel made up of copper is an example of a closed system.

(d)

The presence of reactants in a thermos flask or any other closed insulated vessel is an example of a closed system.

The standard enthalpies of formation of CO₂(g), H₂O(l) and glucose(s) at 25°C are -400 kJ/mol, -300 kJ/mol and -1300 kl/mol^-1 respectively. The standard enthalpy of combustion per gram of glucose of 25°C is ______.

(a)

+2900 kJ

(b)

-2900 kJ

(c)

-16.11 kJ

(d)

+16.11 kJ

Two moles of an ideal gas is expanded isothermally and reversibly from 1 L to 10 L at 300 K. The enthalpy change (in kJ) for the process is______.

(a)

11.4 kJ

(b)

-11.4 kJ

(c)

0 kJ

(d)

4.8 kJ

Which of the following are state functions?

(a)

Enthalpy

(b)

Heat

(c)

Free energy

(d)

Work

In an exothermic reaction, heat is evolved, and system loses heat to the surrounding. For such system______.

(a)

q_p will be negative

(b)

Δ_rH will be negative

(c)

q_p will be positive

(d)

Δ_rH will be positive

On the basis of thermochemical equations (i), (ii) and (iii), find out which of the algebric relationships given in options (a) to (d) is correct.
\( \text { (i) } \mathrm{C} \text { (graphite) }+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g) \Delta_{r} \boldsymbol{H}=\boldsymbol{x} \mathbf{k J} \mathrm{mol}^{-1} \)
\(\text { (ii) } \mathrm{C} \text { (graphite) }+\frac{1}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}(g) \Delta_{r} \boldsymbol{H}=\boldsymbol{y} \mathbf{k J} \mathbf{m o l}^{-1} \)
\(\text { (iii) } \mathrm{CO}(g)+\frac{1}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g) \Delta_{r} \boldsymbol{H}=z \mathrm{~kJ} \mathrm{~mol}^{-1} \)

(a)

z = x + y

(b)

x = y - z

(c)

x = y + z

(d)

y = 2z - x

The pressure-volume work for an ideal gas can be calculated by using the expression w = \(-\int_{v_{t}}^{v_{f}} p_{e x} d V\)- The work can also be calculated from the pV-plot by using the area under the curve within the specified limits. When an ideal gas is compressed (a) reversibly or (b) irreversibly from volume V_i to V_f Choose the correct option.

(a)

w (reversible) = w (irreversible)

(b)

w (reversible) < w (irreversible)

(c)

w (reversible) > w (irreversible)

(d)

w (reversible) = w (irreversible) + \(\boldsymbol{p}_{e x^{}} \Delta \mathbf{V}\)

10.

During complete combustion of one mole of butane, 2658 kJ of heat is released. The thermochemical reaction for above change is ______.

(a)

\( 2 \mathrm{C}_{4} \mathrm{H}_{10}(g)+13 \mathrm{O}_{2}(g) \longrightarrow 8 \mathrm{CO}_{2}(g)+10 \mathrm{H}_{2} \mathrm{O}(l) \Delta_{c} \mathrm{H}=-2658.0 \mathrm{~kJ} \mathrm{~mol}^{-1} \)

(b)

\( \mathrm{C}_{4} \mathrm{H}_{10}(g)+\frac{13}{2} \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{CO}_{2}(g)+5 \mathrm{H}_{2} \mathrm{O}(g) \Delta_{c} \mathbf{H}=-1329.0 \mathrm{~kJ} \mathrm{~mol}^{-1} \)

(c)

\( \mathrm{C}_{4} \mathrm{H}_{10}(\mathrm{~g})+\frac{13}{2} \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{CO}_{2}(g)+5 \mathrm{H}_{2} \mathrm{O}(l) \Delta_{c} \mathrm{H}=-2658.0 \mathrm{~kJ} \mathrm{~mol}^{-1} \)

(d)

\( \mathrm{C}_{4} \mathrm{H}_{10}(g)+\frac{13}{2} \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{CO}_{2}(g)+5 \mathrm{H}_{2} \mathrm{O}(l) \Delta_{c} \mathbf{H}=+2658.0 \mathrm{~kJ} \mathrm{~mol}^{-1} \)

11.

The volume of gas is reduced to half from its original volume. The specific heat will be ___________.

(a)

reduce to half

(b)

be doubled

(c)

remain constant

(d)

increase four times

12.

If the bond energies of H-H, Br-Br and H-Br are 433, 192 and 364 kJ mol^-1, respectively, then \(\Delta \mathbf{H}^{\circ}\) for the reaction. \(\mathbf{H}_{2}(g)+\operatorname{Br}(g) \longrightarrow 2 \mathrm{HBr}(g) \text { is }\) ______.

(a)

-261 kJ

(b)

-103 kJ

(c)

+261 kJ

(d)

-1031 kJ

13.

For the process, \(\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{H}_{2} \mathrm{O}(g) \text { at } \mathrm{T}=100^{\circ} \mathrm{C}\) and 1 atm, the correct choice is ______.

(a)

\( \Delta \mathbf{S}_{\text {System }}>\mathbf{0} \text { and } \Delta \mathbf{S}_{\text {Surr }}<\mathbf{0} \)

(b)

\(\Delta \mathbf{S}_{\text {System }}>\mathbf{0}, \Delta \mathbf{S}_{\text {Surr }}>\mathbf{0} \)

(c)

\(\Delta \mathbf{S}_{\text {System }}<\mathbf{0} \text { and } \Delta \mathbf{S}_{\text {Surr }}>\mathbf{0} \)

(d)

\(\Delta \mathbf{S}_{\text {System }}<\mathbf{0}, \Delta \mathbf{S}_{\text {Surr }}<\mathbf{0} \)

14.

The enthalpy of vapourisation of a liquid is 30 kJ mol^-1 and enthalpy of vapourisation is 75 J mol^-1. The boiling point of the liquid at 1 atm is ______.

(a)

250 K

(b)

400 K

(c)

450 K

(d)

600 K

15.

The correct thermodynamic conditions for the spontaneous reaction at all temperature is ______.

(a)

ΔH < 0 and ΔS > 0

(b)

ΔH < 0 and ΔS < 0

(c)

ΔH < 0 and ΔS = 0

(d)

ΔH > 0 and ΔS < 0

16.

For a given reaction, ΔH = 35.5 kJ mol^-1 and ΔS = 83.6 Jk^-1 mol^-1, The reaction is spontaneous at ______. (assume that ΔH and ΔS do not vary with temperature)

(a)

T > 425 K

(b)

All temperature

(c)

T > 298 K

(d)

T < 425 K

17.

A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy in Joule's will be ______.

(a)

- 500 J

(b)

- 506 J

(c)

+ 505 J

(d)

1136.25 J

18.

Maximum entropy will be in which of the following?

(a)

Ice

(b)

liquid water

(c)

snow

(d)

water vapour

19.

Lattice enthalpies are determined by ______.

(a)

Born-Haber cycle

(b)

Hess' law

(c)

lattice cycle

(d)

None of these

20.

The bond dissociation energies of H₂, CI₂ and HCl are 104, 58 and 103 kcal mol^-1 respectively. The enthalpy of formation of HCI would be ______.

(a)

-22 kcal mol^-1

(b)

- 44 kcal mol^-1

(c)

+44 kcal mol^-1

(d)

+22 kcal mol^-1

21.

Calculate the difference between C_p and C_v for 10 moles of an ideal gas.

(a)

83.14 J

(b)

8.314 J

(c)

831.4 J

(d)

0.831 J

22.

The value of \(\Delta_{r} G^{\circ}\) is equal to ______.

(a)

- 2.303 RT log K

(b)

+ 2.303 RT log K

(c)

\(\Delta_{r} H^{\circ}-T \Delta_{r} S^{\circ}\)

(d)

Both (a) and (c)

23.

For both reversible and irreversible expansion of an ideal gas, under isothermal condition, ______.

(a)

\(\Delta U=0, \Delta S_{\text {total }} \neq 0\)

(b)

\(\Delta U \neq 0, \Delta S_{\text {total }}=0\)

(c)

\(\Delta U \neq 0, \Delta S_{\text {total }}=0\)

(d)

\(\Delta U \neq 0, \Delta S_{\text {total }} \neq 0\)

24.

Entropy is ______.

(a)

a thermodynamic concept

(b)

a state function

(c)

independent of path

(d)

All of the above

25.

What will be the value of logarithm of equilibrium constant K_p if the standard free energy change of a reaction is ΔG^o = -115 kJ at 298 K will be______.

(a)

2.303

(b)

13.83

(c)

2.015

(d)

20.15

26.

Which of the following expression is correct for a reversible process in a state of equilibrium?

(a)

\(\Delta G=-2.30 R T \log K\)

(b)

\(\Delta G=2.30 R T \log K\)

(c)

\(\Delta G^{\circ}=-2.303 R T \log K\)

(d)

\(\Delta G^{\circ}=2.303 R T \log K\)

27.

Which of the following is not correct?

(a)

ΔG is zero for a reversible reaction

(b)

ΔG is positive for a spontaneous reaction

(c)

ΔG is negative for a spontaneous reaction

(d)

ΔG is positive for a non-spontaneous reaction.

28.

Select the incorrect expression from the following

(a)

\(\Delta S_{\text {total }}=\Delta S_{\text {system }}+\Delta S_{\text {surr }}\)

(b)

\(\Delta S_{\text {surr }}=\frac{\Delta H_{\text {surr }}}{T}=-\frac{\Delta H_{\text {sys }}}{T}\)

(c)

\(\Delta S_{\text {total }}<0 \text { (spontaneous process) }\)

(d)

\(\Delta G=\Delta H-T \Delta S\)

29.

The entropy change can be calculated by using the expression \(\Delta S=q_{\mathrm{rev}} / T\) When water freezes in a glass beaker, choose the correct statement amongst the following.

(a)

ΔS (system) decreases but ΔS (surroundings) remains the same

(b)

ΔS (system) increases but ΔS (surroundings) decreases

(c)

ΔS (system) decreases but ΔS (surroundings) increases

(d)

ΔS (system) decreases but ΔS (surroundings) also decreases

30.

The above diagram represents ______.

(a)

enthalpy for exothermic reactions

(b)

enthalpy for endothermic reactions

(c)

entropy for exothermic reactions

(d)

entropy for endothermic reactions

31.

In the given reaction, \(\mathrm{Na}(s) \longrightarrow \mathrm{Na}(g)\) The enthalpy of atomisation is same as the ______.

(a)

enthalpy of dissociation

(b)

enthalpy of sublimation

(c)

enthalpy of association

(d)

enthalpy of vaporisation

32.

Which of the following statement is correct for the reaction?
\( \mathrm{CaO}(s)+\mathrm{CO}_{2}(g) \longrightarrow \mathrm{CaCO}_{3}(s) \Delta_{r} H^{\circ}=-178.3 \mathrm{~kJ} \mathrm{~mol}^{-1} \)

(a)

\(\Delta_{r} H^{\circ} \text { is }\) is the enthalpy of formation of CaCO₃

(b)

\(\Delta_{r} H^{\circ}\) is not the enthalpy of formation of CaCO₃

(c)

\(\Delta_{r} H^{\circ}\)is the enthalpy of combustion of CaCO₃

(d)

None of the above

33.

The enthalpy change when one mole of solute dissolves in a specified amount of solvent is called ______.

(a)

enthalpy of dilution

(b)

enthalpy of solution

(c)

enthalpy of association

(d)

enthalpy of dissociation

34.

For the reaction, \(\mathrm{NaCl}(s) \longrightarrow \mathrm{Na}^{+}(g)+\mathrm{Cl}^{-}(g)\) Identify the enthalpy involved in the above reaction ______.

(a)

enthalpy of hydration

(b)

lattice enthalpy

(c)

enthalpy of solution

(d)

enthalpy of dissociation

35.

Hess's law is based on ______.

(a)

law of conservation of mass

(b)

law of conservation of energy

(c)

law of active mass

(d)

Both (a) and (b)

36.

If the sublimation energy and enthalpy of fusion of I₂ are 57.3 kJ mol^-1 and 15.5kJ mol^-1, respectively then, calculate the enthalpy of vaporisation of I₂______.

(a)

\(-72.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

(b)

\(72.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

(c)

\(-41.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

(d)

\(+41.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

37.

For the given reaction, \(\mathrm{CH}_{4}(g)+2 \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(l)\) the correct expression for \(\Delta_{r} H \text { is }\) ______.

(a)

\( {\left[H_{m}\left(\mathrm{CO}_{2}, g\right)+2 H_{m}\left(\mathrm{O}_{2}, g\right)\right]-\left[2 H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right.} \left.+H_{m}\left(\mathrm{CH}_{4}, g\right)\right] \)

(b)

\( {\left[2 H_{m}\left(\mathrm{O}_{2}, g\right)+H_{m}\left(\mathrm{CH}_{4}, g\right)\right]-\left[H_{m}\left(\mathrm{CO}_{2}, g\right)\right.} \left.+2 H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right] \)

(c)

\( {\left[H_{m}\left(\mathrm{CO}_{2}, g\right)+2 H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right]-\left[H_{m}\left(\mathrm{CH}_{4}, g\right)\right.} \left.+2 H_{m}\left(\mathrm{O}_{2}, g\right)\right] \)

(d)

\( {\left[H_{m}\left(\mathrm{CO}_{2}, g\right)+H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right]-\left[H_{m}\left(\mathrm{CH}_{4}, \mathrm{~g}\right)\right.} \left.+2 H_{m}\left(\mathrm{O}_{2}, g\right)\right] \)

38.

The enthalpies of elements in their standard states are taken as zero. The enthalpy of formation of a compound______.

(a)

is always negative

(b)

is always positive

(c)

may be positive or negative

(d)

is never negative

39.

The mathematical expression of first law of thermodynamics is ______.

(a)

\(\Delta U=q\)

(b)

\(\Delta U=W\)

(c)

\(\Delta U=q+W\)

(d)

\(\Delta U=W_{\mathrm{ad}}\)

40.

For the process to occur under adiabatic conditions, the correct condition is ______.

(a)

Δ T = 0

(b)

Δ p = 0

(c)

q = 0

(d)

w = 0

41.

Choose the correct answer. A thermodynamic state function is a quantity

(a)

used to determine heat changes

(b)

whose value is independent of path

(c)

used to determine pressure volume work

(d)

whose value depends on temperature only

42.

Thermodynamics is not concerned about ______.

(a)

energy changes involved in a chemical reaction

(b)

the extent to which a chemical reaction proceeds

(c)

the rate at which a reaction proceeds

(d)

the feasibility of a chemical reaction

43.

Which one is the correct unit for entropy?

(a)

KJ mol

(b)

JK^-1 mol

(c)

JK^-1 mol ^-1

(d)

KJ mol^-1

44.

The process depicted by the equation.
H₂O (s) \(\rightarrow\) H₂O (l)
\(\Delta\)H = +1.43 kcal represents

(a)

fusion

(b)

melting

(c)

evaporation

(d)

boiling

45.

Which of the following always has a negative value?

(a)

heat of reaction

(b)

heat of solution

(c)

heat of combustion

(d)

heat of formation

46.

Which of the following relation is true?

(a)

C_p > c_u

(b)

c_u > C_p

(c)

C_p = C_u

(d)

C_p = C;_u= 0

47.

Which of the following properties is not a function of state?

(a)

concentration

(b)

internal energy

(c)

enthalpy

(d)

entropy

48.

For a cyclic process, the change in internal energy of the system is ______.

(a)

always +ve

(b)

equal to zero

(c)

always -ve

(d)

none of the above

49.

An isochoric process takes place at constant ______.

(a)

temperature

(b)

pressure

(c)

volume

(d)

concentration

50.

Thermodynamics is applicable to ______.

(a)

macroscopic system only

(b)

microsopic system only

(c)

homogeneous system only

(d)

heterogeneous system only

Assertion and reason

20 x 1 = 20

51.

Assertion : Work and heat are two equivalent form of energy.
Reason : Work is the transfer of mechanical energy irrespective of temperature difference, whereas heat is the transfer of thermal energy because of temperature difference only.
Codes:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.

52.

Assertion : In an adiabatic process, change in internal energy of a gas is equal to work done on or by the gas in th process.
Reason : Temperature of gas remains constant in a adiabatic process.
Codes:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.

53.

Assertion : A room can be cooled by opening the door of a refrigerator in a closed room.
Reason : Heat flows from lower temperature (refrigerator) to higher temperature (room).
Codes:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.

54.

55.

Assertion : In adiabatic compression, the internal energy and temperature of the system get decreased.
Reason : The adiabatic compression is a slow process
Codes:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.

56.

Assertion  :   When a bottle of cold carbonated drink is opened, a slight fog forms around the opening.
Reason  :   Adiabatic expansion of the gas causes lowering of temperature and condensation of water vapours.
Codes:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.

57.

Assertion : Air quickly leaking out of a balloon becomes coolers
Reason : The leaking air undergoes adiabatic expansion.
Codes:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.

58.

Assertion : Reversible systems are difficult to find in real world.
Reason : Most processes are dissipative in nature
Codes:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.

59.

Assertion (A): The second law of thermodynamics states that heat can be completely converted into work.
Reason (R): No engine can be 100% efficient.
Codes:
(a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.

60.

Assertion (A): In an isothermal process, the internal energy of an ideal gas remains unchanged.
Reason (R): Internal energy of an ideal gas depends only on temperature.
Codes:
(a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.

61.

Assertion (A): In an adiabatic process, no heat is exchanged between the system and its surroundings.
Reason (R): The temperature of the system remains constant during an adiabatic process.
(a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.

62.

Assertion : The sum of q + w is a state function.
Reason : Work and heat are state functions.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

63.

Assertion : Sublimation of the solid is nonspontaneous.
Reason : Sublimation is endothermic process.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

64.

Assertion : U is a state function.
Reason : T is an intensive property.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

65.

Assertion : Decrease in free energy causes spontaneous reaction.
Reason : Spontaneous reactions are invariable exothermic reactions.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

66.

Assertion : Some salts are sparingly soluble in water at room temperature.
Reason : The entropy increases on dissolving the salts.
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

67.

Assertion : Enthalpy of formation of graphite is zero but of diamond it is not zero.
Reason : Enthalpy of formation of the most stable allotrope is taken as zero.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

68.

Assertion: Combustion of all organic compounds is an exothermic reaction.
Reason: The enthalpies of all elements in their standard state are zero.
Codes:
(a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Both Assertion and Reason are false.

69.

Assertion: Heat capacity is the amount of heat required to raise the temperature of a body by 1 K.
Reason: Heat capacity is an extensive property and it depends upon the size of the body.
Codes:
(a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Both Assertion and Reason are false.

70.

Assertion: An isolated system is the one which can neither exchange matter nor energy with the surroundings.
Reason: It should be noted that every system is perfectly isolated.
Codes:
(a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Both Assertion and Reason are false.

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Answers Key:

Multiple Choice Question

50 x 1 = 50

(b)
\(\mathrm{N}_{2}(g, 1 \mathrm{~atm}) \longrightarrow \mathrm{N}_{2}(g, 5 \mathrm{~atm})\)

(b)
-11.4 kJ

(a)
Enthalpy

(a)
q_p will be negative

(b)
w (reversible) < w (irreversible)

10.

(b)
\( \mathrm{C}_{4} \mathrm{H}_{10}(g)+\frac{13}{2} \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{CO}_{2}(g)+5 \mathrm{H}_{2} \mathrm{O}(g) \Delta_{c} \mathbf{H}=-1329.0 \mathrm{~kJ} \mathrm{~mol}^{-1} \)

11.

(d)
increase four times

12.

(b)
-103 kJ

13.

(b)
\(\Delta \mathbf{S}_{\text {System }}>\mathbf{0}, \Delta \mathbf{S}_{\text {Surr }}>\mathbf{0} \)

14.

(b)
400 K

15.

(b)
ΔH < 0 and ΔS < 0

16.

(b)
All temperature

17.

(b)
- 506 J

18.

(d)
water vapour

19.

(a)
Born-Haber cycle

20.

(a)
-22 kcal mol^-1

21.

(a)
83.14 J

22.

(d)
Both (a) and (c)

23.

(a)
\(\Delta U=0, \Delta S_{\text {total }} \neq 0\)

24.

(d)
All of the above

25.

(d)
20.15

26.

27.

(b)
ΔG is positive for a spontaneous reaction

28.

29.

30.

(a)
enthalpy for exothermic reactions

31.

(b)
enthalpy of sublimation

32.

(b)
\(\Delta_{r} H^{\circ}\) is not the enthalpy of formation of CaCO₃

33.

(b)
enthalpy of solution

34.

(b)
lattice enthalpy

35.

(b)
law of conservation of energy

36.

(d)
\(+41.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

37.

(c)
\( {\left[H_{m}\left(\mathrm{CO}_{2}, g\right)+2 H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right]-\left[H_{m}\left(\mathrm{CH}_{4}, g\right)\right.} \left.+2 H_{m}\left(\mathrm{O}_{2}, g\right)\right] \)

38.

39.

40.

41.

(b)
whose value is independent of path

42.

(b)
the extent to which a chemical reaction proceeds

43.

44.

(a)
fusion

45.

46.

(a)
C_p > c_u

47.

(a)
concentration

48.

(b)
equal to zero

49.

50.

(a)
macroscopic system only

Assertion and reason

20 x 1 = 20

51.

C) If assertion is true but reason is false.
Explanation:
Heat is similar to work in that both represent ways of transferring energy. Neither heat nor work is an intrinsic property of a system, that is, we cannot say that a system contains a certain amount of heat or work

52.

C) If assertion is true but reason is false.
Explanation:
In an adiabatic process, no exchange of heat is permissible i.e.,

ΔQ=0
. As,

ΔQ=ΔU+ΔW=0
Þ

ΔU=−ΔW
. Also in adiabatic process, temperature of gas changes.

53.

D) If the assertion and reason both are false.
Explanation:
When the door of refrigerator is kept open, heat rejected by the refrigerator to the room will be more than the heat taken by the refrigerator from the room (by an amount equal to work done by the compressor). Therefore, temperature of room will increase and so it will be warmed gradually. As according to 2nd law of thermodynamics, heat cannot be transferred on its own, from a body at lower temperature to another at higher temperature.

54.

A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
Explanation:
Heat is similar to work in that both represent ways of transferring energy. Neither heat nor work is an intrinsic property of a system, that is, we cannot say that a system contains a certain amount of heat or work

55.

D) If the assertion and reason both are false.
Explanation:
Adiabatic compression is a rapid action and both the internal energy and the temperature increases.

56.

A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
Explanation:
When a bottle of cold carbonated drink is opened. A slight fog forms around the opening. This is because of adiabatic expansion of gas causes lowering of temperature and condensation of water vapours.

57.

A) If both assertion and reason are true and the reason is the correct explanation of the assertion
Explanation:
Adiabatic expansion produces cooling.

58.

A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
Explanation:
In a perfectly reversible system, there is no loss of energy. Losses can be minimised, friction can be reduced, the resistance in L-C oscillating system can also be negligible. But one cannot completely eliminate energy losses. This makes a perfectly reversible system, an ideal.

59.

(d) Assertion (A) is false, but Reason (R) is true.
Explanation: The second law forbids complete conversion of heat into work; it actually supports the idea that no engine is 100% efficient. So the assertion is incorrect, while the reason is correct

60.

(a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
Explanation:
Since temperature is constant in an isothermal process, and internal energy U of an ideal gas depends only on temperature, ΔU=0.

61.

(c) Assertion (A) is true, but Reason (R) is false.
Explanation: Adiabatic processes involve no heat exchange ( Q=0 ), but the temperature does change because internal energy changes due to work.

62.

(c) Assertion is correct statement but reason is wrong statement.
Explanation:
∆E = q + w Internal energy is a state function, but not q or w.

63.

(d) Assertion is wrong statement but reason is correct statement.
Explanation:
Sublimation of the solid is spontaneous due to increase in entropy.

64.

(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.

65.

(c) Assertion is correct statement but reason is wrong statement.
Explanation:
Exothermic reactions are spontaneous at low temperature but becomes non-spontaneous at high temperature.

66.

(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.

67.

(a) Graphite is the most stable form.

68.

(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

69.

(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

70.