Heat of transition is the heat evolved or absorbed when a substance is converted from

Based on the following thermochemical equations,find the value of $x$ in $kJ$.
$(i) \ H_2O_{(g)} + C_{(s)} \to CO_{(g)} + H_{2(g)} ; \Delta H = 131 \ kJ$
$(ii) \ CO_{(g)} + \frac{1}{2} O_{2(g)} \to CO_{2(g)} ; \Delta H = -282 \ kJ$
$(iii) \ H_{2(g)} + \frac{1}{2} O_{2(g)} \to H_2O_{(g)} ; \Delta H = -242 \ kJ$
$(iv) \ C_{(s)} + O_{2(g)} \to CO_{2(g)} ; \Delta H = -x \ kJ$

Which of the following equations corresponds to the definition of enthalpy of formation at $298 \ K$?

Given the following thermochemical equations:
$(i) \ Zn + \frac{1}{2}O_2 \rightarrow ZnO + 84000 \ cal$
$(ii) \ Hg + \frac{1}{2}O_2 \rightarrow HgO + 21700 \ cal$
Calculate the heat of reaction $(\Delta H)$ for the reaction: $Zn + HgO \rightarrow ZnO + Hg$. (in $cal$)

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 $.... \ kJ$.

Which of the following equations correctly represents the standard heat of formation $(\Delta H_f^o)$ of methane?