Which of the following pairs of a chemical reaction is certain to

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 Multiple Choice QuestionsMultiple Choice Questions

151.

For the reaction,

C2H5OH (l) + 3O2 (g) → 2CO2 (g) + 3H2O (l)

which one is true?

  • H = E - RT

  • H = E + RT

  • H = E + 2RT

  • H = E - 2RT


152.

What is the entropy change (in JK-1 mol-1) when one mole of ice is converted into water at 0°C? (The enthalpy change for the conversion of ice to liquid water is 6.0 kJ mol-1 at 0°C).

  • 20.13

  • 2.013

  • 2.198

  • 21.98


153.

The molar heat capacity (C) of water at constant pressure, is 75 JK-1 mol-1. When 1.0 kJ of heat is supplied to 100 g of water which is free to expand, the increase in temperature of water is

  • 1.2 K

  • 2.4 K

  • 4.8 K

  • 6.6 K


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154.

Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?

  • Endothermic and decreasing disorder

  • Exothermic and increasing disorder

  • Endothermic and increasing disorder

  • Exothermic and decreasing disorder


B.

Exothermic and increasing disorder

Among the given options, option b is the correct option.

Entropy is the measurement of disorderness as it increases entropy increases and if disorderness decreases entropy will decrease.

For a spontaneous reaction, value of free energy change (G) is always negative.

G = H -TS

For negative value of G, value of H should be negative and value of S should be positive.

Negative value of H indicates exothermic reaction and positive value of S indicates increase in disorderness.


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155.

Identify the correct statement for change of Gibbs energy for a system (Gsystem) at constant temperature and pressure

  • If Gsystem = 0, the system has attained equilibrium

  • If Gsystem = 0, the system is still moving in a particular direction

  • If Gsystem = 0, the process is not spontaneous

  • If Gsystem = 0, the process is spontaneous


156.

To which of the following determinations of heat, Hess's law is used?

  • Heat of chemical reaction

  • Heat of formation

  • Heat of bond formation

  • All of the above


157.

C2H252O2 → 2CO2 + H2O ; ΔH = -310 Kcal

C + O2 → CO2 ; ΔH = -94 Kcal

H212O2  →   H2O ; ΔH = -68 Kcal

On the basis of the above equations, ΔHf (enthalpy of formation) of C2H2 ,will be

  • -148 Kcal

  • +54 Kcal

  • -54 Kcal

  • +80 Kcal


158.

I2(s) I2(g) ΔH= + 40Kcal, ΔS= 80cal. The sublimation point of I2(s) will be

  • 100°C

  • 127°C

  • 227°C

  • 500°C


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159.

In a reversible isothermal process, the change in internal energy is

  • zero 

  • positive

  • negative

  • None of these


160.

Based on the following thermochemical equations

H2O (g) + C(s) → CO (g) + H2 (g); H = 131 kJ

CO (g) + 12 O2(g) → CO2 (g); H = -282 kJ

H2 (g) + 12O2 (g) → H2O (g); H =-242 kJ

C (s) + O2 (g) → CO(g); H = X kJ

the value of X will be

  • -393 kJ

  • -655 kJ

  • +393 kJ

  • +655 kJ


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