Reversible expansion of an ideal gas under isothermal and adiabatic conditions are as shown in the figure: AB → Isothermal expansion AC → Adiabatic expansion Which of the following options is not correct?

∆ S i s o t h e r m a l > ∆ S a d i a b a t i c

W i s o t h e r m a l > W a d i a b a t i c

Hydrolysis of sucrose is given by the following reaction Sucrose + H 2 O ⇌ Glucose + Fructose If the equilibrium constant (K c ) is 2 × 10 13 at 300 K, the value of ∆ r G ⊝ at the same temperature will be:

-8.314 J mol -1 K -1 × 300 K × ln (2 × 10 13 )

8.314 J mol -1 K -1 × 300 K × ln (2 × 10 13 )

8.314 J mol -1 K -1 × 300 K × ln (3 × 10 13 )

-8.314 J mol -1 K -1 × 300 K × ln (4 × 10 13 )

Chemistry - Thermodynamics - Quiz-9

The heat of combustion of carbon to CO₂ is -393.5 KJ/mol. The heat changed upon the formation of 35.2 g of CO₂ from carbon and oxygen gas is -

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-315 KJ
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+315 KJ
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-630 KJ
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+630 KJ

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

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$∆$ G = - 2.30RT log K
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$∆$ G = 2.30RT log K
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$∆$ G^o = - 2.30RT log K
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$∆$ G^o = 2.30RT log K

Which of the following statements is correct for the spontaneous adsorption of a gas ?

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$∆$ S is negative and therefore, $∆$ H should be highly positive
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$∆$ S is negative and therefore, $∆$ H should be highly negative
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$∆$ S is positive and therefore, $∆$ H should be negative
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$∆$ S is positive and therefore, $∆$ H should also be highly positive

For the reaction :

X₂O₄(l) → 2XO₂(g)

ΔU = 2.1 kcal, ΔS = 20 cal K^–1 at 300 K

The value of ΔG is -

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2.7 kcal
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-2.7 kcal
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9.3 kcal
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-9.3 kcal

In which of the following reactions, standard reaction entropy changes $(∆ S^{0})$ is positive and standard Gibb's energy change $(∆ G^{0})$ decreases sharply with increasing temperature?

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$C (g r a p h i t e) + \frac{1}{2} O_{2} (g) \to C O (g)$
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$C O (g) + \frac{1}{2} O_{2} (g) \to C O_{2} (g)$
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$M g (s) + \frac{1}{2} O_{2} (g) \to M g O (s)$
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$\frac{1}{2} C (g r a p h i t e) + \frac{1}{2} O_{2} (g) \to \frac{1}{2} C O_{2} (g)$

The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0^oC is

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10.52 cal/(mol K)
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21.04 cal/(mol K)
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5.260 cal/(mol K)
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0.526 cal/(mol K)

Given the following reaction:
4H(g)→ 2H₂ (g) is - 869.6 kJ
The enthalpy change for the reaction is -869.6 kJ. The dissociation energy of the H-H bond is -

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-869.6 kJ
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+434.8kJ
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+217.4kJ
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-434.8 kJ

Standard entropies of X₂, Y₂ and XY₃ are 60, 40 and 50JK^-1mol^-1 respectively. For the reaction
$\frac{1}{2} X_{2} + \frac{3}{2} Y_{2} ⇋ {XY}_{3}; ∆ H = - 30 kJ$ to be at equilibrium, the temperature should be

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750 K
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1000 K
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1250 K
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500 K

From the following bond energies :

H—H bond energy: 431.37 kJ mol^-1
C=C bond energy: 606.10 kJ mol^-1
C—C bond energy: 336.49 kJ mol^-1
C—H bond energy: 410.50 kJ mol^-1

Enthalpy for the reaction,

will be

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1523.6 kJ mol^-1
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-243.6 kJ mol^-1
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-120.0 kJ mol^-1
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553.0 kJ mol^-1

The values of ΔH and ΔS for the reaction, C_(graphite) + CO₂(g)→2CO(g) are 170 kJ and 170 JK^-1, respectively. This reaction will be spontaneous at

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710 K
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910 K
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1110 K
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510 K

For the gas phase reaction,

{PCl}_{5} (g) ⇌ {PCl}_{3} (g) + {Cl}_{2} (g)

which of the following conditions are correct?

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ΔH = 0 and ΔS < 0
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ΔH > 0 and ΔS > 0
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ΔH < 0 and ΔS < 0
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ΔH > 0 and ΔS < 0

The standard free energies of formation(in kJ/mol) at 298 K are -237.2, -394.4 and -8.2 for H₂O(l), CO₂(g) and pentane (g), respectively. The value of E_cell for the pentane-oxygen fuel cell is:

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1.968 V
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2.0968 V
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1.0968 V
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0.0968 V

Bond dissociation enthalpy of H₂, Cl₂ and HCl are 434, 242 and 431 kJ mol¹ respectively. Enthalpy of formation of HCl is

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93 kJ mol^-1
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- 245 kJ mol^-1
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-93 kJ mol^-1
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245 kJ mol^-1

The bond energy of H—H and Cl-Cl is 430 kJ mol^-1 and 240 kJ mol^-1 respectively and ΔH_f for HCl is -90 kJ mol^-1. The bond enthalpy of HCl is :

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290 $k J m o l^{- 1}$
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380 $k J m o l^{- 1}$
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425 $k J m o l^{- 1}$
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245 $k J m o l^{- 1}$

Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?

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Carbon and hydrogen suitable reducing agents for metal sulphides
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The $∆_{f} G^{0}$ of the sulphide is greater than those for $C S_{2}$ and $H_{2} S$
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the $∆_{f} G^{0}$ is negative for roasting of sulphur ore to oxide.
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Roasting of the sulphide to the oxide is thermodynamically feasible

Assume each reaction is carried out in an open container. For which reaction will ΔH=ΔE ?

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$H_{2} (g) + B r_{2} (g) \to 2 H B r (g)$
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$C (s) + 2 H_{2} O (g) \to 2 H_{2} (g) + C O_{2} (g)$
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$P C l_{5} (g) \to P C l_{3} (g) + C l_{2} (g)$
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$2 C O (g) + O_{2} (g) \to 2 C O_{2} (g)$

Under isothermal condition, a gas at 300 K expands from 0.1 L to 0.25 L against a constant external pressure of 2 bar. The work done by the gas is: [Given that 1 L bar=100 J]

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30 J
0%

-30 J
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5 kJ
0%

25 J

In which case, change in entropy is negative?

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$2 H (g) \to H_{2} (g)$
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Evaporation of water
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Expansion of a gas at a constant temperature
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Sublimation of solid to gas

2.1 g of Fe combines with S evolving 3.77 kJ. The heat of formation of FeS in kJ/mole is–

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– 3.77
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– 1.79
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– 100.5
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None of the above

Which is an extensive property?

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Temperature
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Chemical potential
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Gibbs free energy
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Molar volume

An ideal gas expands isothermally from $10^{- 3} m^{3} t o 10^{- 2} m^{3}$ at 300 K against a constant pressure of $10^{5} N m^{- 2}$ . The work done by the gas is:

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+270 kJ
0%

-900 J
0%

+900 kJ
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-900 kJ

Reversible expansion of an ideal gas under isothermal and adiabatic conditions are as shown in the figure:

AB $\to$ Isothermal expansion

AC $\to$ Adiabatic expansion

Which of the following options is not correct?

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$∆ S_{i s o t h e r m a l} > ∆ S_{a d i a b a t i c}$
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$T_{A} = T_{B}$
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$W_{i s o t h e r m a l} > W_{a d i a b a t i c}$
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$T_{C} > T_{A}$

A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant

temperature of 37.0ºC. As it does so, it absorbs 208 J of heat. The values of q and w for the process will be-
(R = 8.314 J/mol K) (ln 7.5 = 2.01)

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q = +208 J, w = -208 J
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q = -208 J, w = -208 J
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q = -208 J, w = + 208 J
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q = +208 J, w = + 208 J

The pair of isochoric among the transformation of state is:

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K to L and L to M
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L to M and N to K
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L to M and M to N
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M to N and N to K

Hydrolysis of sucrose is given by the following reaction

Sucrose + H₂O $⇌$ Glucose + Fructose

If the equilibrium constant (K_c) is 2 $\times$ 10¹³ at 300 K, the value of $∆_{r} G^{⊝}$ at the same temperature will be:

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8.314 J mol^-1 K^-1 $\times$ 300 K $\times$ ln (2 $\times$ 10¹³)
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8.314 J mol^-1 K^-1 $\times$ 300 K $\times$ ln (3 $\times$ 10¹³)
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-8.314 J mol^-1 K^-1 $\times$ 300 K $\times$ ln (4 $\times$ 10¹³)
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-8.314 J mol^-1 K^-1 $\times$ 300 K $\times$ ln (2 $\times$ 10¹³)

For the reaction, 2Cl(g) $\to$ Cl₂(g), the correct option is:

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$∆_{r} H > 0 and ∆_{r} S < 0$
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$∆_{r} H < 0 and ∆_{r} S > 0$
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$∆_{r} H < 0 and ∆_{r} S < 0$
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$∆_{r} H > 0 and ∆_{r} S > 0$

The solubility of a solute in water varies with temperature and is given as $S = {Ae}^{- ∆ H / RT} .$

Here, $∆ H$ is enthalpy of the solution. For the given solute variation of log, S with temperature can be shown by the figure given below.

This solute may be

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CaSO₄
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CuSO₄
0%

CuSO₄5H₂O
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MgO

The equilibrium constant for the reaction

$H_{2} (g) + S (g) ⇌ H_{2} S (g)$

is 18.5 at 925 and 9.25 at 1000 respectively. What is the enthalpy of the reaction?

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-142.16 kJ/mole
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-71.08 kJ/mole
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-35.54 kJ/mole
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none of these

If the value of $∆$ H in a reaction is positive, then the reaction is called

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Exothermic
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Endothermic
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Polymorphic
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Polytropic

Molar heat capacity at constant P for a substance is equal to

$(1) {(∆ U / ∆ T)}_{v} (2) {(∆ H / ∆ T)}_{V} (3) {(∆ H / ∆ T)}_{P} (4) {(∆ U / ∆ T)}_{P}$

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1
0%
2
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3
0%
4

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Practice Chemistry Quiz Questions and Answers

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Practice Chemistry Quiz Questions and Answers

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