Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsMultiple Choice Questions

1.

The correct thermodynamic conditions for  the spontaneous reaction at all temperatures is

  • ΔH> 0 and Δ S< 0
  • ΔH< 0 and ΔS > 0
  • ΔH ΔS >0
  • ΔH ΔS >0
1844 Views

2.

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

  • ΔG = -2.303RT log K
  • ΔG = 2.303RT log K

  • ΔG0 = -2.303RT log K

  • ΔG0 = -2.303RT log K

1043 Views

3.

Which of the following statement is correct for the spontaneous absorption of a gas?

  • ΔS is negative and therefore, ΔH should be highly positive
  • ΔS is negative and therefore, ΔH should be highly negative
  • ΔS is positive and therefore, ΔH should be negative
  • ΔS is positive and therefore, ΔH should be negative
1139 Views

Advertisement

4.

For the reaction X2O4 (l) -->  2XO2 (g) ΔU = 2.1 kcal, ΔS = 20 cal K-1 at 300 K hence ΔG is

  • 2.7 kcal

  • -2.7kcal

  • 9.3 kcal 

  • 9.3 kcal 


B.

-2.7kcal

The change in Gibbs free energy is given by

ΔG = ΔH-TΔS

Where, ΔH = enthalpy of the reaction

ΔS = entropy of reaction
Thus, in order to determine ΔG, the values of ΔH must be known. The value of ΔH can be calculated by the equation
ΔH = ΔU + ΔngRT
Where (ΔU) = change in internal energy

Δng = (number of moles of gaseous products)-(number of moles of gaseous reactant) = 2-0 =2
R = gas constant = 2 cal
But, ΔH= Δu +  ΔngRT 
Δu  =2.1 kcal = 2.1 x 103 cal

[1kcal = 103 cal]
therefore,
ΔH = (2.1 x 103) +(2x2x300) =3300 cal
Hence, ΔG = ΔH-TΔS
 ΔG = (3300)-(300 x20)
 ΔG =-2700 cal
 ΔG =-2.7 Kcal

4144 Views

Advertisement
Advertisement
5.

A reaction having equal energies of activation for forward and reverse reactions has

  • ΔS =0
  • ΔG =0
  • ΔH = 0
  • ΔH = 0
2213 Views

6.

In which of the following reactions, standard reaction entropy changes (ΔSo) is positive and standard Gibb's energy change (ΔGo) decreases sharply with increasing temperature?

  • C (graphite) +1/2 O2 (g) → CO (g)

  • CO (g) +1/2 (g) → CO2 (g)

  • Mg(s)  +1/2O2 (g) → MgO (s)

  • Mg(s)  +1/2O2 (g) → MgO (s)

1457 Views

7.

The enthalpy of fusion of water is 1.435 Kcal/mol. The molar entropy change for the melting of ice of at 0o C is

  • 10.52 cal/(mol K)

  • 21.04 cal/(mol K)

  • 5.260 cal/ (mol K)

  • 5.260 cal/ (mol K)

861 Views

8.

Standard enthalpy of vaporisation ΔvapHθ for water for water at 100oC is 40.66 kJ mol-1. The internal energy of vaporisation of water at 100o C (in KJ mol-1) is

(Assume water vapour to behave like an ideal gas.)

  • +37.56

  • -43.76

  • +43.76

  • +43.76

594 Views

Advertisement
9.

If the enthalpy change for the transition of liquid water to steam is 30kJ mol-1 at 27oC, the entropy change for the process would be. 

  • 1.0 J mol- K-1

  • 0.1 J mol-1 K-1

  • 100 J  mol-1 K-1

  • 10 J mol-1 K-1

553 Views

10.

Which of the following is the correct option for free expansion of an ideal gas under an adiabatic condition?

750 Views

Advertisement