If a process is both endothermic and spontaneous, then :

1. $∆S>0$

2. $∆S<0$

3. $∆H<0$

4. $∆G>0$

The bond energies of C=C and C-C at 298 K are 590 and 331 kJ mol^-1 respectively. The enthalpy of polymerization per mole of ethylene is

1. -70 kJ

2. -72 kJ

3. 72 kJ

4. -68 kJ

The gas absorbs 100 J heat and is simultaneously compressed by a constant external pressure of 1.50 atm from 8 lit. to 2 lit. in volume. Hence $∆E$ will be-

1. -812 J

2. 812 J

3. 1011 J

4. 911 J

The standard heat of combustion of Al is -837.8 kJ mol^-1 at ${25}^{\circ }C$ which of the following releases 250 kcal of heat ?

1. The reaction of 0.624 mol of Al

2. The formation of 0.624 mol of Al₂O₃

3. The reaction of 0.312 mol of Al

4. The formation of 0.150 mol of Al₂O₃

Following reaction occurs at ${25}^{\circ }C$ :

$$\begin{gathered} 2NO\left(g, 1\times {10}^{-5} atm\right)+C{l}_2\left(g, 1\times {10}^{-2} atm\right) \\ \rightleftharpoons 2NOCl\left(g, 1\times {10}^{-2} atm\right) \\ {∆}^{\circ }G is : \end{gathered}$$

1. -45.65 kJ

2. -28.53 kJ

3. -22.82 kJ

4. -57.06 kJ

The bond energies of$C\equiv C$, C-H, H-H and C=C are 198, 98, 103 and145 kcal respectively. The enthalpy change of the reaction $HC\equiv CH+H_2\to C_2{H}_4$ is:

1. 48 kcal

2. 96 kcal

3. -40 kcal

4. -152 kcal

The enthalpies of formation of CO₂(g) and CO(g) at 298 K are in the ratio 2.56 : 1. For the reaction,

$C{O}_2\left(\mathrm{(g)}\right)+C\left(\mathrm{(s)}\right)\to 2CO\left(\mathrm{(g)}\right), ∆H=177.5kJ,$
$∆H_f of CO\left(\mathrm{(g) }\right)i\mathrm{s-}$

1. -150.6 kJ mol^-1

2. -113.78 kJ mol^-1

3. -130.2 kJ mol^-1

4. -141.8 kJ mol^-1

The enthalpies of the following reactions are shown alongwith.

$\frac{1}{2}{H}_2\left(g\right)+\frac{1}{2}{O}_2\left(g\right)\to OH\left(g\right) ; ∆H=42.09 kJ mo{l}^{-1}$
$H_2\left(g\right)\to 2H\left(g\right); ∆H=435.89 kJ mo{l}^{-1}$
$O_2\left(g\right)\to 2O\left(g\right); ∆H=495.05 kJ mo{l}^{-1}$

Calculate the O-H bond energies for the hydroxyl radical.

1. 223.18 kJ mol^-1

2. 423.38 kJ mol^-1

3. 513.28 kJ mol^-1

4. 113.38 kJ mol^-1

4.8 g of C(diamond) on complete combustion evolves 1584 kJ of heat. The standard heat of formation gaseous carbon is 725 kJ/mol. The energy required for the process

(i) $\mathrm{C}\left(\mathrm{graphite}\right)\to \mathrm{C}\left(\mathrm{gas}\right)$

(ii) $\mathrm{C}\left(\mathrm{diamond}\right)\to \mathrm{C}\left(\mathrm{gas}\right)$are

1. 725, 727

2. 727, 725

3. 725, 723

4. None of these

The reaction $3{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{O}}_3\left(\mathrm{g}\right)$ is endothermic. What can be concluded about the average energy per bond in ${\mathrm{O}}_2 \mathrm{and} {\mathrm{O}}_3$?

1. The average energy per bond in ${\mathrm{O}}_2$ is greater than that in ${\mathrm{O}}_3$

2. The average energy per bond in ${\mathrm{O}}_2$ is less than that in ${\mathrm{O}}_3$

3. The average energy per bond in ${\mathrm{O}}_2$ is equal to that is ${\mathrm{O}}_3$

4. Number conclusion can be drawn about the average bond energies from this information done