The following thermochemical reactions are given:
$M + \frac{1}{2} O_2 \to MO + 351.4 \ kJ$ $(i)$
$X + \frac{1}{2} O_2 \to XO + 90.8 \ kJ$ $(ii)$
It follows that the heat of reaction for the following process $M + XO \rightleftharpoons MO + X$ is given by $... \ kJ$.

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 :

The heat of combustion of solid benzoic acid at constant volume is $-321.30 \ kJ$ at $27^{\circ} C$. The heat of combustion at constant pressure is $(-321.30 - x R) \ kJ$. The value of $x$ is . . . . . . .

Average $C-H$ bond energy is $416 \ kJ \ mol^{-1}$. Which of the following is correct?

Enthalpy of a compound is equal to its

Calculate the standard enthalpy change of the following reaction: $CH_{4(g)} + 2O_{2(g)} \rightarrow CO_{2(g)} + 2H_{2}O_{(\ell)}$ if $\Delta_{f} H^{\circ}(CH_{4}) = -75 \ kJ \ mol^{-1}$,$\Delta_{f} H^{\circ}(CO_{2}) = -390 \ kJ \ mol^{-1}$,and $\Delta_{f} H^{\circ}(H_{2}O) = -286 \ kJ \ mol^{-1}$.