Which of the following is an endothermic reaction?

$\mathrm{N}_2(g)+3 \mathrm{H}_2(g)-92 \mathrm{~kJ} \longrightarrow 2 \mathrm{NH}_3(g)$
$\mathrm{N}_2(g)+\mathrm{O}_2(g)+180.8 \mathrm{~kJ} \longrightarrow 2 \mathrm{NO}(g)$
$\mathrm{H}_2(g)+\mathrm{Cl}_2(g) \longrightarrow 2 \mathrm{HCl}(g)+184.6 \mathrm{~kJ}$
$\mathrm{C}$ (graphite) $+2 \mathrm{H}_2(g) \longrightarrow \mathrm{CH}_2(g)+74.8 \mathrm{~kJ}$

Solution

Endothermic reactions are those in which heat energy is absorbed.

Asked in: AP EAMCET 2004