The bond dissociation energies of $X_2 , Y_2$ and XY are in the ratio of 1 : 0.5 : 1. ∆H for the formation of XY is –200 kJ mol^–1. The bond dissociation energy of X₂ will be

1. 200 kJ mol^–1
2. 100 kJ mol^–1
3. 800 kJ mol^–1
4. 400 kJ mol^–1

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:
1. -315 KJ
2. +315 KJ
3. -630 KJ
4. +630 KJ

The correct statement for a reversible process in a state of equilibrium is:
1. $∆$G = - 2.30RT log K
2. $∆$G = 2.30RT log K
3. $∆$G^o = - 2.30RT log K
4. $∆$G^o = 2.30RT log K

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

Given the reaction: 
X₂O₄(l) → 2XO₂(g) 
ΔU = 2.1 kcal, ΔS = 20 cal K^–1 at 300 K 
The value of ΔG is:
1. 2.7 kcal
2. -2.7 kcal
3. 9.3 kcal
4. -9.3 kcal

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

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

1. 10.52 cal/(mol K)

2. 21.04 cal/(mol K)

3. 5.260 cal/(mol K)

4. 0.526 cal/(mol K)

Given the following reaction:
\(4H(g)\)→  \(2 H_{2}\)\((g)\)
The enthalpy change for the reaction is -869.6 kJ. The dissociation energy of the H-H bond is:
1. -869.6 kJ
2. +434.8kJ
3. +217.4kJ
4. -434.8 kJ

Standard entropies of X₂, Y₂ and XY₃ are 60, 40 and 50JK^-1mol^-1 respectively. For the reaction 
$\frac{1}{2}{\mathrm{X}}_2$ $+$ $\frac{3}{2}{\mathrm{Y}}_2$ $$ $\leftrightharpoons$ ${\mathrm{XY}}_3$ $;$ $∆\mathrm{H}$ $=$ $-30$ $\mathrm{kJ}$ to be at equilibrium, the temperature should be:

1. 750 K

2. 1000 K

3. 1250 K

4. 500 K