JEE Main 2025 — 8 April, Evening Shift — Question 21

Resonance in $X_{2} Y$ can be represented as

The enthalpy of formation of $X_{2} Y$ $\left(X \equiv X(g)+\frac{1}{2} Y=Y(g) \rightarrow X_{2} Y(g)\right)$ is $80 \mathrm{~kJ} \mathrm{~mol}^{-1}$.

The magnitude of resonance energy of $X_{2} Y$ is $\ldots \mathrm{kJ} \mathrm{mol}^{-1}$ (nearest integer value) Given : Bond energies of

$X \equiv X, X=X, Y=Y$ and $X=Y$ are 940, 410, 500 and $602 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively.

Valence $\mathrm{X}: 3, \mathrm{Y}: 2$