The heat of neutralisation of HCl by NaOH is -55.9 kJ/mole. If the heat of neutralisation of HCN by NaOH is -12.1 kJ/mole, then energy of dissociation of HCN is-

1. -43.8 kJ

2. 43.8 kJ

3. 68 kJ

4. -68 kJ

In which case of mixing of a strong acid and a base, each of 1(N) concentration, temperature-increase is the highest ?

1. 20 ml acid and 30 ml alkali

2. 10 ml acid and 40 ml alkali

3. 25 ml acid and 25 ml alkali

4. 35 ml acid and 15 ml alkali

The heats of neutralisation of four acids A, B, C and D are -13.7, -9.4, -11.2 and -12.4 kcal respectively when they are neutralised by a common base. The acidic character obeys the order :

1. A>B>C>D

2. A>D>C>B

3. D>C>B>A

4. D>B>C>A

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