Chemistry - Hydrogen and Its compound Question with Solution | TestHub

The $\mathrm{H}-\mathrm{X}$ bond strength decreases from $\mathrm{HF}$ to HI. i.e. $\mathrm{HF}>\mathrm{HCl}>\mathrm{HBr}>\mathrm{HI}$. Thus $\mathrm{HF}$ is most stable while HI is least stable. The decreasing stability of the hydrogen halide is also reflected in the values of dissociation energy of the $\mathrm{H}-\mathrm{X}$ bond $$\begin{array}{cccc}\mathrm{H}-\mathrm{F}& \mathrm{H}-\mathrm{Cl}& \mathrm{H}-\mathrm{Br}& \mathrm{H}-\mathrm{I}\\ 135\mathrm{kcal}{\mathrm{mol}}^{-1}& 103\mathrm{kcal}{\mathrm{mol}}^{-1}& 87\mathrm{kcal}{\mathrm{mol}}^{-1}& 71\mathrm{kcal}{\mathrm{mol}}^{-1}\end{array}$$