Which of the following represents the correct order of bond energy?

Hydrofluoric acid $(HF)$ cannot be stored in glass bottles because it reacts with glass $(SiO_2)$ to form:

Identify the correct decreasing order of bond dissociation enthalpy from the following.

$A$ solid $A$ which has photographic effect reacts with the solution of a sodium salt $B$ to give a pale yellow precipitate $C$. The sodium salt $B$ on heating with concentrated $H_2SO_4$ gives brown vapours. Identify $A$,$B$,and $C$.

$HBr$ and $HI$ reduce sulphuric acid,$HCl$ can reduce $KMnO_4$ and $HF$ can reduce:

Explain the electron gain enthalpy values of elements of the $17^{\text{th}}$ group. Give reasons and explain.