If standard enthalpy of formation $(\Delta_{f} H^{\circ})$ of $CO_2, H_2 O$ and $CH_4$ are $-393, -286$ and $-74.0 \ kJ \ mol^{-1}$ respectively,the standard enthalpy of combustion of methane in $kJ \ mol^{-1}$ is

Given
$(i) \, 2Fe_2O_{3(s)} \to 4Fe_{(s)} + 3O_{2(g)}$
$\Delta _rG^o = + 1487.0 \, kJ \, mol^{-1}$
$(ii) \, 2CO_{(g)} + O_{2(g)} \to 2CO_{2(g)}$
$\Delta _rG^o = - 514.4 \, kJ \, mol^{-1}$
Free energy change,$\Delta _rG^o$ for the reaction
$2Fe_2O_{3(s)} + 6CO_{(g)} \to 4Fe_{(s)} + 6CO_{2(g)}$ will be ..... $kJ \, mol^{-1}$

What will be the $C-H$ bond enthalpy if:
$CH_{4(g)} + 2O_{2(g)} \rightarrow CO_{2(g)} + 2H_2O_{(l)};$ $\Delta H = -890 \, kJ$
$CO_{2(g)} \rightarrow C_{(graphite)} + O_{2(g)};$ $\Delta H = 393 \, kJ$
$2H_2O_{(l)} \rightarrow 2H_{2(g)} + O_{2(g)};$ $\Delta H = 571 \, kJ$
$2H_{2(g)} \rightarrow 4H_{(g)};$ $\Delta H = 871 \, kJ$
$C_{(graphite)} \rightarrow C_{(g)};$ $\Delta H = 716 \, kJ$

Standard molar enthalpy of formation of $CO_2$ is equal to

For the reaction $R \rightarrow P$,the following potential energy diagram is given. What will be the enthalpy change $(\Delta H)$ for the given reaction (in $kJ$)?

On the basis of the thermochemical equations:
$H_{2}O_{(g)} + C_{(s)} \to CO_{(g)} + H_{2(g)} \quad \Delta H = 131 \ kJ$
$CO_{(g)} + \frac{1}{2} O_{2(g)} \to CO_{2(g)} \quad \Delta H = -282 \ kJ$
$H_{2(g)} + \frac{1}{2} O_{2(g)} \to H_{2}O_{(g)} \quad \Delta H = -242 \ kJ$
$C_{(s)} + O_{2(g)} \to CO_{2(g)} \quad \Delta H = X \ kJ$
The value of $X$ will be $.... \ kJ$.