For which of the reactions below is(are) the heat of reaction equal to the heat of formation?

$\text{ (P) }\frac{1}{2}{\mathrm{N}}_2\left(g\right)+{\mathrm{O}}_2\left(g\right)⟶{\mathrm{NO}}_2\left(g\right)$  $\mathrm{\Delta }H>0$

$\text{ (Q) }{\mathrm{SO}}_2\left(g\right)+\frac{1}{2}{\mathrm{O}}_2\left(g\right)⟶{\mathrm{SO}}_3\left(g\right)$  $\mathrm{\Delta }H<0$

$\frac{1}{2}\mathrm{N}\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{NO}}_2\left(\mathrm{g}\right){\mathrm{\Delta H}}_{{\mathrm{NO}}_2}^{\mathrm{f}}=\mathrm{x}$

${\mathrm{N}}_2+{\mathrm{O}}_2\to 2\mathrm{NO}\left(\mathrm{g}\right){\mathrm{\Delta H}}_{\mathrm{fNo}}=\frac{\mathrm{y}}{2}$

$2\mathrm{NO}\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)⟶2{\mathrm{NO}}_2\left(\mathrm{g}\right){\mathrm{\Delta H}}_{\text{reaction }}=\mathrm{z}$

${\mathrm{\Delta H}}_{\text{reaction }}=\sum {\mathrm{\Delta H}}_{\text{product }}-\sum {\mathrm{\Delta H}}_{\text{reactant }}$

$z=2x-2x\frac{y}{2}$

$2x=y+z$

So, $\frac{1}{2}{\mathrm{N}}_2\left(g\right)+{\mathrm{O}}_2\left(g\right)⟶{\mathrm{NO}}_2\left(g\right)$ in this reaction is(are) the heat of reaction equal to the heat of formation.