For a given reaction, if ΔH = 35.5 kJ/mol and ΔS = 83.6 J/K·mol, at what temperature is the reaction spontaneous?
(Assume ΔH and ΔS remain constant with temperature.)

A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy $∆$U of the gas in joules will be

(1) 1136.25 J

(2) - 500 J

(3) - 505 J

(4) + 515 J

For the reaction, X₂O₄(l) $\to$2XO₂(g)

$∆$U = 2.1 kcal, $∆$S = 20 cal K^-1 at 300 K. Hence, $∆$G is

1. 2.7 kcal

2. -2.7 kcal

3. 9.3 kcal

4. -9.3 kcal

If the enthalpy change for the transition of liquid water to steam is 30 kJ mol^-1 at 27°C,

the entropy change for the process would be

1. 1.0 J mol^-1 K^-1

2. 0.1 J mol^-1K^-1

3. 100 J mol^-1K^-1

4. 10 J mol^-1K^-1

 Which of the following options correctly describes the free expansion of an ideal gas under adiabatic conditions?
1. \(\mathrm{q} \neq 0, \quad \Delta \mathrm{T}=0, \quad \mathrm{~W}=0\)
2. \(\mathrm{q}=0, \quad \Delta \mathrm{T}=0, \quad \mathrm{~W}=0\)
3. \(\mathrm{q}=0, \quad \Delta \mathrm{T}<0, \quad \mathrm{~W} \neq 0\)
4. \(\mathrm{q}=0, \quad \Delta \mathrm{T} \neq 0, \quad \mathrm{~W}=0\)

Enthalpy change for the reaction,

 4H(g) $\to$2H₂(g) is -869.6 kJ

The dissociation energy of H-H bond is

1. -869.6 kJ                 

2. + 434.8 kJ

3. +217.4 kJ                 

4. -434.8 kJ

Given the following bond energies:

Based on the data given above, enthalpy change for the following reaction will be:
 

1. 1523.6 kJ mol^-1

2. -243.6 kJ mol^-1

3. -120.0 kJ mol^-1

4. 553.0 kJ mol^-1

Which of the following are not state functions?

(I) q + W                        (II) q

(III) W                           (IV) H-TS

1. (I) and (IV)                     

2. (II), (III) and (IV)

3. (I) , (II) and (III)               

4.  (II) and (III)

Consider the following reactions :

(i) ${\mathrm{H}}^{+}\left(\mathrm{aq}\right) + {\mathrm{OH}}^{-}\left(\mathrm{aq}\right) = {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) ∆\mathrm{H} = -{\mathrm{x}}_1 \mathrm{kJ} {\mathrm{mol}}^{-1}$

(ii) ${\mathrm{H}}_2\left(\mathrm{g}\right) + \frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right) = {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) ∆\mathrm{H} = -{\mathrm{x}}_2 \mathrm{kJ} {\mathrm{mol}}^{-1}$

(iii) ${\mathrm{CO}}_2\left(\mathrm{g}\right) + {\mathrm{H}}_2\left(\mathrm{g}\right) = \mathrm{CO}\left(\mathrm{g}\right) + {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) ∆\mathrm{H} = -{\mathrm{x}}_{3 }\mathrm{kJ} {\mathrm{mol}}^{-1}$

(iv) ${\mathrm{C}}_2{\mathrm{H}}_5\left(\mathrm{g}\right) + \frac{5}{2}{\mathrm{O}}_2\left(\mathrm{g}\right) = 2{\mathrm{CO}}_2\left(\mathrm{g}\right) + {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) ∆\mathrm{H} = -{\mathrm{x}}_4 \mathrm{kJ} {\mathrm{mol}}^{-1}$

Enthalpy of formation of H₂O(l) is:

1. -x₂ kJ mol^-1 

2. +x₃ kJ mol^-1

3. -x₄ kJ mol^-1

4. -x₁ kJ mol^-1

Identify the correct statement for change of Gibbs energy for a system ($∆$G_system) at constant temperature and pressure:

(1) If $∆$G_system > 0, the process is spontaneous

(2) If $∆$G_system = 0, the system has attained equilibrium

(3) If $∆$G_system = 0, the system is still moving in a particular direction

(4) If $∆$G_system < 0, the process is not spontaneous