The heat of atomisation of methane and ethane are $x \ kJ \ mol^{-1}$ and $y \ kJ \ mol^{-1}$ respectively. The longest wavelength $(\lambda)$ of light capable of breaking the $C-C$ bond can be expressed in $SI$ unit as :

Hess's law is based on

Consider the reaction $2H_2S(g) + 3O_2(g) \rightarrow 2H_2O(l) + 2SO_2(g)$. The magnitude of enthalpy change for the reaction in $\text{kJ mol}^{-1}$ is . . . . . . . (Nearest integer). Given: $\Delta_f H^\circ(H_2S) = -20.1 \text{ kJ mol}^{-1}$, $\Delta_f H^\circ(H_2O) = -286.0 \text{ kJ mol}^{-1}$, $\Delta_f H^\circ(SO_2) = -297.0 \text{ kJ mol}^{-1}$

Given,
$NO_{(g)} + O_{3(g)} \longrightarrow NO_{2(g)} + O_{2(g)}; \Delta H = -198.9 \, kJ/mol$
$O_{3(g)} \longrightarrow 3/2 O_{2(g)}; \Delta H = -142.3 \, kJ/mol$
$O_{2(g)} \longrightarrow 2O_{(g)}; \Delta H = +495.0 \, kJ/mol$
The enthalpy change $(\Delta H)$ for the following reaction is $..... \, kJ/mol$
$NO_{(g)} + O_{(g)} \longrightarrow NO_{2(g)}$

Calculate $\Delta H$ for the reaction: $H_{2(g)} + O_{2(g)} \rightarrow H_2O_{2(g)}$ given the bond energies: $BE_{H-H} = 436 \ kJ/mol$,$BE_{O=O} = 499 \ kJ/mol$,$BE_{O-O} = 142 \ kJ/mol$,and $BE_{O-H} = 460 \ kJ/mol$. (in $kJ$)

Calculate the standard enthalpy of combustion of carbon monoxide $(CO)$ given that $\Delta_f H^{\circ}(CO) = -110 \text{ kJ mol}^{-1}$ and $\Delta_f H^{\circ}(CO_2) = -393 \text{ kJ mol}^{-1}$.