The enthalpy of vaporization of benzene is +35.3 kJ/mol at its boiling point of $80°\mathrm{C}$. The entropy change in the transition of vapour to liquid at its boiling point is

1. -100

2. +100

3. +342

4. -342

A piece of metal weighing 100 g is heated to $80°\mathrm{C}$ and dropped into 1 kg of cold water in an insulated container at $15°\mathrm{C}$. If the final temperature of the water in the container is $15.69°\mathrm{C}$, the specific heat of metal in J/g.$°\mathrm{C}$ is

1. 0.38

2. 0.24

3. 0.45

4. 0.13

The maximum work (in kJ ${\mathrm{mol}}^{-1}$) that can be derived from complete combustion of 1 mol of CO at 298 K and 1 atm is

[standard enthalpy of combustion of CO=-283.0 kJ ${\mathrm{mol}}^{-1}$; standard molar entropies at 298 K: ${\mathrm{S}}_{{\mathrm{O}}_2}=205.1 \mathrm{J} {\mathrm{mol}}^{-1}, {\mathrm{S}}_{\mathrm{CO}}=197.7 \mathrm{J} {\mathrm{mol}}^{-1}$, ${\mathrm{S}}_{{\mathrm{CO}}_2}=213.7 \mathrm{J} {\mathrm{mol}}^{-1}$]

1. - 257

2. 227

3. 257

4. 127

An ideal gas is taken through the cycle $\mathrm{A}\to \mathrm{B}\to \mathrm{C}$ as shown in figure, if net heat supplied to the gas in the cycle is 5 J, the work done by the gas in the process $\mathrm{C}\to \mathrm{A}$ is

1. -5 J

2. -10 J

3. -15 J

4. -20 J

The amount of heat required to raise the temperature of 1 mole diatomic gas by $1°\mathrm{C}$ at constant pressure is 60 cal. The amount of heat which goes as internal energy of the gas is nearly

1. 60 cal

2. 30 cal

3. 42.6 cal

4. 49.8 cal

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

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 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

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 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