For the process A (1, 0.05 atm, 32°C) → A (g, 0.05 atm,

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391.

For the process A (1, 0.05 atm, 32°C) → A (g, 0.05 atm, 32°C)

The correct set of thermodynamic parameters is

  • G = 0 and S = -ve

  • G = 0 and S = +ve

  • G = +ve and S = 0

  • G = -ve and S = 0


B.

G = 0 and S = +ve

(i) Since, n and T are constants. 

 G = 0

Hence, the system is equilibrium.

(ii) Since, P → decreases

 S → increases, i.e. it is +ve

Therefore, among all the options given, the correct answer is in option b, i.e. G = 0 and S = +ve.


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392.

The standard enthalpy of formation of H2O (l) and Fe2O3 (s) are respectively -286 kJ mol-1 and -824 kJ mol-1. What is the standard enthalpy change for the following reaction?

Fe2O3 (s) + 3H2 (g) → 3H2O (l) + 2Fe (s)

  • -538 kJ mol-1

  • +538 kJ mol-1

  • -34 kJ mol-1

  • +34 kJ mol-1


393.

Thermal decomposition of ammonium dichromate gives

  • N2, H2O and Cr2O3

  • N2, NH3 and CrO

  • (NH4)2CrO4 and H2O

  • N2, H2O and CrO3


394.

The enthalpy change for a reaction at equilibrium is -20.5 kJ mol-1. Then the entropy change for this equilibrium at 410 K is

  • +50 JK-1mol-1

  • +55 JK-1mol-1

  • +75 JK-1mol-1

  • -50 JK-1mol-1


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395.

The enthalpy of combustion of glucose (mol.wt.: 180 g mol-1) is -2840 kJ mol-1. Then the amount of heat evolved when 0.9 g ofglucose is burnt, will be

  • 14.2 kJ

  • 142 kJ

  • 28.4 kJ

  • 1420 kJ


396.

The entropy of vaporisation of a liquid is 58 JK-1 mol-1. If 100 g of its vapour condenses at its boiling point of 123° C, the value of entropy change for the process is

  • -100 JK-1

  • 100 JK-1

  • -123 JK-1

  • 123 JK-1


397.

At constant external pressure of one atmosphere, 4 moles of a metallic oxide MO2 undergoes complete decomposition at 227°C in an open vessel according to the equation

2MO2 (s) → 2MO (s) + O2 (g)

The work done by the system in kJ is (R = 8.3 kJ mol-1)

  • -16.6

  • -24.9

  • -33.2

  • -4.15


398.

A certain reaction has a H of 12 kJ and a S of 40 JK-1. The temperature above which the reaction becomes spontaneous is

  • 27°C

  • 27 K

  • 300°C

  • 30 K


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399.

Mathematical equation of first law of thermodynamics for isochoric process is

  • ΔU = qv

  • -ΔU = qv

  • q= -W

  • ΔU = W


400.

The criterion for a spontaneous process is

  • ΔG >0 

  • ΔG < 0

  • ΔG = 0

  • ΔStotal < 0


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