Chemistry Question from JEE Main 2025 · 8 April, Shift 2

Resonance in $X_2Y$ can be represented as

The enthalpy of formation of $X_2Y$ $\left( X \equiv X(g) + \tfrac{1}{2} Y = Y(g) \rightarrow X_2Y(g) \right)$ is $80 \, \text{kJ mol}^{-1}$. The magnitude of resonance energy of $X_2Y$ is _____ $\text{kJ mol}^{-1}$ (nearest integer value).

Given: Bond energies of $X \equiv X$, $X = X$, $Y = Y$ and $X = Y$ are $940$, $410$, $500$ and $602 \, \text{kJ mol}^{-1}$ respectively.

Valency of $X$: $3$, of $Y$: $2$.