Thermodynamics - Chemistry - Live Session

Incorrect statement among the following is :

1.	Pv work is usually negligible for solid and liquid.
2.	For a closed system with P-V work only, an isobaric process that has q= +ve must have $\Delta \mathrm{T}=+\mathrm{ve}$.
3.	For a cyclic process q= - w.
4.	Black phosphorus is most stable form of P but $\mathrm{H}_{\mathrm{f}}^{\circ}=0 $ for white phosphorus.

Temperature and heat are :
1. Extensive properties
2. Intensive properties
3. Intensive and extensive properties respectively
4. Extensive and intensive properties respectively

In a flask, colourless N $_{2}$ O $_{4}$ (g) is in equilibrium with brown coloured NO $_{2}$ (g) . At
equilibrium when the flask is heated to 100 $°$ C, the brown colour deepens and on
colling it becomes coloured. Which statement is incorrect about this observation?
1. The $∆$ H for the reaction N $_{2}$ O $_{4}$ (g) $⇌$ 2NO $_{2}$ (g) is + ve
2. Paramagnetism increases on cooling
3. The $∆$ H- $∆$ U at 100 $°$ C is equal to 200 cal
4. Dimerisation is reduced on heating

The incorrect expression among the following is:
1. In isothermal process,
$W_{reversible} = - nRT \ln \frac{V_{f}}{V_{i}}$
2. $\ln K = \frac{∆ H ° - T ∆ S °}{RT}$
3. $K = e^{- ∆ G ° l RT}$
4. $\frac{∆ G_{system}}{∆ S_{total}} = - T$

Enthalpy of vaporisation for water is 186.5 kJ ${mol}^{- 1}$ . The entropy change during vaporisation in kJ $K^{- 1}$ ${mol}^{- 1}$ is -
(1) 0.5
(2) 1.0
(3) 1.5
(4) 2.0

The standard change is Gibbs energy for the reaction, $H_{2} O ⇌ H^{+} + {OH}^{-} at 25$ $° C$ is :
(1) 100kJ
(2) -90kJ
(3) 90kJ
(4)-100 kJ

For a reaction at $25 ° C$ enthalpy change ( $∆$ H) and entropy change ( $∆$ S) are $- 11.7 \times 10^{3} J m o l^{- 1}$ and $- 105 J m o l^{- 1} K^{- 1}$
respectively. The reaction is:
(1) Spontaneous
(2) Non-spontaneous
(3) Instantaneous
(4) None of the above

The entropy change for the reaction given below,
$2 H_{2} (g) + O_{2} (g) \to 2 H_{2} O (l)$
is ..... at 300 K. Standard entropies of $H_{2} (g), O_{2} (g)$ and $H_{2} O (l) a r e 126.6, 201.20 a n d 68.0 J K^{- 1} m o l^{- 1}$ respectively.
(1) $- 318.4 J K^{- 1} m o l^{- 1}$
(2) $318.4 J K^{- 1} m o l^{- 1}$
(3) $31.84 J K^{- 1} m o l^{- 1}$
(4) None of these

A Carnot engine operates between temperature T and 400 K (T > 400 K). If efficiency of engine is 25%, the temperature T is:
1. 400 K
2. 500 K
3. 533.3 K
4. 600 K

10.

The work is done in an open vessel at 300 K, when 112 g irone reacts with dil. HCI is:
1. 1.2 kcal
2. 0.6 kcal
3. 0.2 kcal
4. 2 kcal

11.

Boiling point of a liquid is 50 K at 1 atm and $∆ H_{v a p .} = 460.6 c a l m o l^{- 1}$ . what will be its b.p at 10 atm?
(1) 150 K
(2) 75 K
(3) 100 K
(4) 200 K

12.

The internal energy change when a system goes from state A to B is 40 kJ/mol. If the system goes from A to B by a reversible path and returns to state A by an irreversible path and returns to state A by an irreversible path. What would be the net change in internal energy?
1. 40 kJ
2. >40 kJ
3. <40 kJ
4. Zero

13.

At 1 atm pressure, $∆ S = 75 J K^{- 1} m o l^{- 1}; ∆ H = 30 K J m o l^{- 1} .$
The temperature of the reaction at equilibrium is :
(1) 400 K
(2) 330 K
(3) 200K
(4) 110 K

14.

$S \tan d a r d e n t r o p y X_{2} Y_{2} a n d X Y_{3} a r e 60, 40 a n d 50 J K^{- 1} m o l^{- 1} r e s p e c t i v e l y . F o r t h e r e a c t i o n, \frac{1}{2} X_{2} + \frac{3}{2} Y_{2} \to X Y_{3}, ∆ H = 30 K J, t o b e a t e q u i l i b r i u m, t h e t e m p e r a t u r e w i l l b e :$
(1) 1000K
(2) 1250 K
(3) 500 K
(4) 750 K

15.

$T h e f a c t o r {(\frac{\partial Q}{\partial T})}_{P} - {(\frac{\partial Q}{\partial T})}_{V} i s e q u a l t o :$
1. $γ$
2. R
3. $\frac{R}{M}$
4. $∆ nRT$

16.

Which plot represents an exothermic reaction?
1.
2.
3.
4.

17.

For a given substance, melting point $T_{B}$ and freezing point is $T_{A}$ , which of the following represents the correct variation of $∆ S$ vs T?
1.
2.
3.
4.

18.

Which of the following is correct for an ideal gas?
1. ${(\frac{\partial E}{\partial T})}_{V} = 0$
2. ${(\frac{\partial E}{\partial P})}_{T} = 0$
3. ${(\frac{\partial E}{\partial T})}_{P} = 0$
4. All of these

19.

The difference between heat of reaction at constant pressure and constant volume for the reaction given below at 25 $° C$ in kJ is:
$2 C_{6} H_{6} (l) + 15 O_{2} (g) \to 12 {CO}_{2} (g) + 6 H_{2} O (l)$
(1) -7.43
(2) +3.72
(3) -3.72
(4) +7.43

20.

The value of $∆ H °$ for the reaction $C u^{+} (g) + I^{-} (g) \to C u I (g)$ is -446kJ $m o l^{- 1}$ . If the ionisation energy of Cu(g) is 745 kJ $m o l^{- 1}$ and the electron affinity of I(g) is -295kJ $m o l^{- 1}$ , then the value of $∆ H °$ for the formation of one mole CuI(g) from Cu(g) and I(g) is:
(1) -446 kJ $m o l^{- 1}$
(2) 450 kJ $m o l^{- 1}$
(3) 594 kJ $m o l^{- 1}$
(4) 4 kJ $m o l^{- 1}$

21.

Given enthalpy of formation of ${CO}_{2}$ (g) and CaO(s) are -84.0kJ and -152kJ respectively and the enthalpy of the reaction,
${CaCO}_{3} (s) \to CaO (s) + {CO}_{2} (g)$ is 42 kJ. The enthalpy of formation of $C a C O_{3}$ (s) is:
1. -42 kJ
2. -202 kJ
3. +202 kJ
4. -288 kJ

22.

The heat of combustion for C, $H_{2}$ and $H_{2} O$ are -349.0, -241.8 and -906.7 kJ respectively. the heat of formation of $C H_{4}$ is:
(1) 174.1 kJ
(2) 274.1 kJ
(3) 374.1 kJ
(4) 74.1 kJ

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