Question

Enthalpy of formation of $HF$ and $HCl$ are $-161\, kJ$ and $-92 \,kJ$, respectivelv. Select the incorrect statement on the basis of the above fact.

• A. $HF$ is more stable than $HCl$
• B. $HCl$ is more stable than $HF$
• C. Affinity of fluorine to hydrogen is greater than affinity of chlorine to hydrogen
• D. $HF$ and $HCl$ are exothermic compound

Answer 1

Answer: (B)

$HF$ is more stable than $HCl$ because more energy is produced in the formation of $HF$.
It means HF has less energy than $HCl$ and hence is more stable.
So, we need more energy to break $H - F$ bond. Hence, $HF$ is more stable.