For which one of the following reactions, the entropy change is p

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 Multiple Choice QuestionsMultiple Choice Questions

131.

Calculate enthalpy for formation of ethylene from the following data

(I) C(graphite) + O2(g)  CO2(g);   H = 393.5 kJ(II) H2(g) + 12O2(g)  H2O (l);  H = -286.2 kJ(III) C2H4(g) + 3O2(g)  2CO2(g) + 2H2O (l): H = -1410.8 kJ

  • 54.1 kJ

  • 44.8 kJ

  • 51.4 kJ

  • 48.4kJ


132.

A system is provided with 50 J of heat and the work done on the system is 10 J. What is the change in internal energy of the system in Joules?

  • 60

  • 40

  • 50

  • 10


133.

Calculate H° for the reaction,

Na2O (s) + SO3 (g) → Na2SO4 (g) given the following-

(A) Na (s) + H2O (l) → NaOH (s) + 12H2 (g) ; H° = -146 kJ

(B) Na2SO4 (s) + H2O (l) → 2NaOH (s) + SO3 (g) ; H° = +418 kJ

(C) 2Na2O (s) + 2H2 (g) → 4Na (s) + 2H2O (l); H° = +259 kJ

  • +823 kJ

  • -581 kJ

  • -435 kJ

  • +531 kJ


134.

C6H6 + O3 → X Zn/ H2O Y; X and Y are respectively.

  • diozonide, glycol

  • triozonide, glyoxalic acid

  • triozonide, glyoxal

  • monoozonide, oxalic acid


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135.

What is the entropy change in JK-1 during the melting of 27.3 g of ice at 0°C? (Latent heat of fusion of ice = 330 Jg-1)

  • 330

  • 12.1

  • 3.3

  • 33


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136.

For which one of the following reactions, the entropy change is positive?

  • H2 (g) + 12O2 (g) → H2O (l)

  • Na+ (g) + Cl- (g) → NaCl (s)

  • NaCl (l) → NaCl (s)

  • H2O (l) → H2O (g)


D.

H2O (l) → H2O (g)

Evaporation of water in an open vessel is a process which takes place by itself, by absorption of heat from the surroundings, because the gaseous water molecules are more random than the liquid water molecules.

H2O (l) → H2O (g), H = +40.8 kJ mol-1

The process is spontaneous because it is accompained by increase of entropy, which is further a measure of randomness or disorder of the system.


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137.

Molar heat capacity (Cp) of water at constant pressure is 75 JK-1mol-1. The increase in temperature (in K) of 100 g of water when 1 kJ of heat is supplied to it is

  • 2.4

  • 0.24

  • 1.3

  • 0.13


138.

Calculate G° for the following cell reaction:

Zn (s) + Ag2O (s) + H2O (l) → Znn2+ (aq) + 2Ag (s) + 2OH- (aq)

EAg+/ Ag° = 0.80 V and EZn2+/ Zn° = -0.76 V

  • -305 kJ/ mol

  • -301 kJ/ mol

  • 305 kJ/ mol

  • 301 kJ/ mol


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139.

The temperature of K at which ΔG = 0, for a given reaction with ΔH =- 20.5 kJ mol-1 and ΔS=-500 JK-1mol-1 is

  • -410

  • 410

  • -2.44

  • 2.44


140.

In a reaction, A + B C + D, D, 40% of B has reacted at equilibrium, when 1 mole of A was heated with 1 mole of B in a 10 L closed vessel. The value of Kc is

  • 0.44

  • 0.18

  • 0.22

  • 0.36


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