For irreversible expansion of an ideal gas under isothermal condition, the correct option is :

1. $∆\mathrm{U}=0, ∆{\mathrm{S}}_{\mathrm{total}}\ne 0$

2. $∆\mathrm{U}\ne 0, ∆{\mathrm{S}}_{\mathrm{total}}=0$

3. $∆\mathrm{U}=0, ∆{\mathrm{S}}_{\mathrm{total}}=0$

4. $∆\mathrm{U}\ne 0, ∆{\mathrm{S}}_{\mathrm{total}}\ne 0$

For the reaction, 2Cl(g) $\to$ Cl₂(g), the correct option is:

1. ${∆}_{\mathrm{r}}\mathrm{H}>0 \mathrm{and} {∆}_{\mathrm{r}}\mathrm{S}<0$

2. ${∆}_{\mathrm{r}}\mathrm{H}<0 \mathrm{and} {∆}_{\mathrm{r}}\mathrm{S}>0$

3. ${∆}_{\mathrm{r}}\mathrm{H}<0 \mathrm{and} {∆}_{\mathrm{r}}\mathrm{S}<0$

4. ${∆}_{\mathrm{r}}\mathrm{H}>0 \mathrm{and} {∆}_{\mathrm{r}}\mathrm{S}>0$

If for a certain reaction ${∆}_{r}H$ is 30 kJ mol^–1 at 450 K, the value of ${∆}_{r}S$ (in JK^–1 mol^–1) for which the same reaction will be spontaneous at the same temperature is:

1. 70

2. –33

3. 33

4. -70

For a sample of a perfect gas when its pressure is changed isothermally from P_i to P_f, the entropy change is given by:

1. $∆\mathrm{s}=\mathrm{nR}$ $\mathrm{In}$ $\left(\frac{{\mathrm{p}}_{\mathrm{f}}}{{\mathrm{p}}_{\mathrm{i}}}\right)$

2. $∆\mathrm{s}=\mathrm{nR}$ $\mathrm{In}$ $\left(\frac{{\mathrm{p}}_{\mathrm{i}}}{{\mathrm{p}}_{\mathrm{f}}}\right)$

3. $∆\mathrm{s}=\mathrm{nRT}$ $\mathrm{In}$ $\left(\frac{{\mathrm{p}}_{\mathrm{f}}}{{\mathrm{p}}_{\mathrm{i}}}\right)$

4. $∆\mathrm{s}=\mathrm{RT}$ $\mathrm{In}$ $\left(\frac{{\mathrm{p}}_{\mathrm{i}}}{{\mathrm{p}}_{\mathrm{f}}}\right)$

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

Match List – I (Equations) with List – II (Type of processes) and select the correct option.

A reaction occurs spontaneously if:

1. T∆S > ∆H and ∆H is +ve and ∆S are –ve

2. T∆S = ∆H and both ∆H and ∆S are +ve

3. T∆S < ∆H and both ∆H and ∆S are +ve

4. T∆S > ∆H and both ∆H and ∆S are +ve

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

1. Endothermic and decreasing disorder

2. Exothermic and increasing disorder

3. Endothermic and increasing disorder

4. Exothermic and decreasing disorder

Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is:

1. ${\mathrm{\Delta S}}_{\mathrm{system }}-{\mathrm{\Delta S}}_{\mathrm{surrounding }}>0$

2. ${\mathrm{\Delta S}}_{\mathrm{system }}>0\mathrm{ only }$

3. ${\mathrm{\Delta S}}_{\mathrm{surroundings }}>\mathrm{O}$ $\mathrm{only}$

4. ${\mathrm{\Delta S}}_{\mathrm{system }}+{\mathrm{\Delta S}}_{\mathrm{surrounding }}>0$

What is the entropy change (in JK^–1 mol^–1) when one mole of ice is converted into water at 0 ºC? (The enthalpy change for the conversion of ice to liquid water is 6.0 KJ mol^–1 at 0 ºC)