Bond energy of covalent $O-H$ bond in water is

The melting point of $o$-hydroxybenzaldehyde $(A)$ is lower than that of $p$-hydroxybenzaldehyde $(B)$. This is because

Which of the following hydrogen bonds is likely to be the weakest?

The boiling points of methanol,water,and dimethyl ether are respectively $65\,^{\circ}C$,$100\,^{\circ}C$,and $-24.8\,^{\circ}C$ (note: dimethyl ether is a gas at room temperature). Which of the following best explains these wide variations in boiling point $(b.p.)$?

The number of $H_2O$ molecules participating in hydrogen bonding in $CuSO_4 \cdot 5H_2O$ is/are

Which is the weakest among the following types of bond?