Given that the bond energy of hydrogen-hydrogen bond is $436 \ kJ/mol$,that of hydrogen-oxygen bond is $464 \ kJ/mol$,and those in oxygen molecules $496 \ kJ/mol$,what is the approximate heat of reaction for $2H_2 + O_2 \longrightarrow 2H_2O$ ? .....$kJ/mol$

The standard enthalpies of combustion of $C_6H_{6(l)}$,$C(graphite)$ and $H_{2(g)}$ are respectively $-3270 \ kJ \ mol^{-1}$,$-394 \ kJ \ mol^{-1}$ and $-286 \ kJ \ mol^{-1}$. What is the standard enthalpy of formation of $C_6H_{6(l)}$ in $kJ \ mol^{-1}$?

The heats of combustion of rhombic and monoclinic sulphur are respectively $70960 \ cal$ and $71030 \ cal$. What will be the heat of conversion of rhombic sulphur to monoclinic? $(cal)$

$C(\text{diamond}) + O_{2(g)} \to CO_{2(g)}; \Delta H = -395 \text{ kJ}$
$C(\text{graphite}) + O_{2(g)} \to CO_{2(g)}; \Delta H = -393.5 \text{ kJ}$
If graphite is converted into diamond,then the $\Delta H$ for the process is . . . . . . $\text{kJ}$.

The heat of formation for the reaction $H_2 + Cl_2 \to 2HCl + 44 \ kcal$ is ..... $kcal \ mol^{-1}$.

Given:
$(i) \, C(\text{graphite}) + O_{2(g)} \to CO_{2(g)}; \Delta_r H^\ominus = x \, kJ \, mol^{-1}$
$(ii) \, C(\text{graphite}) + \frac{1}{2} O_{2(g)} \to CO_{(g)}; \Delta_r H^\ominus = y \, kJ \, mol^{-1}$
$(iii) \, CO_{(g)} + \frac{1}{2} O_{2(g)} \to CO_{2(g)}; \Delta_r H^\ominus = z \, kJ \, mol^{-1}$
Based on the above thermochemical equations,find out which one of the following algebraic relationships is correct?