5 questions from 2026
Consider the following data.
(i) \( 2\mathrm{Al(s)} + 6\mathrm{HCl(aq)} \rightarrow \mathrm{Al_2Cl_6(aq)} + 3\mathrm{H_2(g)} + 1200 \, \text{kJ} / \text{mol} \)
(ii) \( \mathrm{H_2(g)} + \mathrm{Cl_2(g)} \rightarrow 2\mathrm{HCl(g)} + 164 \, \text{kJ} / \text{mol} \)
(iii) \( \mathrm{HCl(g)} + \text{aq} \rightarrow \mathrm{HCl(aq)} + 83 \, \text{kJ} / \text{mol} \)
(iv) \( \mathrm{Al_2Cl_6(s)} + \text{aq} \rightarrow \mathrm{Al_2Cl_6(aq)} + 663 \, \text{kJ} / \text{mol} \)
The enthalpy of formation of anhydrous solid \( \mathrm{Al_2Cl_6} \) is:
Consider the reaction \( 2\mathrm{H_2S(g)} + 3\mathrm{O_2} \rightarrow 2\mathrm{H_2O(l)} + 2\mathrm{SO_2(g)} \)
The magnitude of enthalpy change for the reaction in \( \mathrm{kJ\,mol^{-1}} \) is ______. (Nearest integer)
[Given: \( \Delta_\mathrm{f}H^\ominus(\mathrm{H_2S}) = -20.1 \ \mathrm{kJ\,mol^{-1}} \), \( \Delta_\mathrm{f}H^\ominus(\mathrm{H_2O}) = -286.0 \ \mathrm{kJ\,mol^{-1}} \) and \( \Delta_\mathrm{f}H^\ominus(\mathrm{SO_2}) = -297.0 \ \mathrm{kJ\,mol^{-1}} \)]
The heat of atomization of methane and ethane are ‘\( x \)’ \( \mathrm{kJ\,mol^{-1}} \) and ‘\( y \)’ \( \mathrm{kJ\,mol^{-1}} \) respectively. The longest wavelength (\( \lambda \)) of light capable of breaking the C–C bond can be expressed in SI unit as:
Consider the following data:
\( \Delta_{\text{f}}\text{H}^{\ominus} (\text{methane}, \text{g}) = -\text{X} \text{ kJ mol}^{-1} \)
Enthalpy of sublimation of graphite = \( y \, \text{kJ mol}^{-1} \)
Dissociation enthalpy of \( \text{H}_{2} \) = \( z \, \text{kJ mol}^{-1} \)
The bond enthalpy of C–H bond is given by:
If \( 3.365 \, \text{g} \) of ethanol \((l)\) is burnt completely in a bomb calorimeter at \( 298.15 \, \text{K} \), the heat produced is \( 99.472 \, \text{kJ} \). The \( \left| \Delta H_f^{\circ} \right| \) of ethanol at \( 298.15 \, \text{K} \) is ________ \( \times 10^{2} \) \( \text{kJ} \, \text{mol}^{-1} \). (Nearest integer)
Given: Standard enthalpy for combustion of graphite = \( -393.5 \, \text{kJ} \, \text{mol}^{-1} \)
Standard enthalpy of formation of water \((l)\) = \( -285.8 \, \text{kJ} \, \text{mol}^{-1} \)
Molar mass in \( \text{g} \, \text{mol}^{-1} \) of C, H, O are \( 12 \), \( 1 \) and \( 16 \) respectively
