Water $(H_2O)$ is a liquid while hydrogen sulfide $(H_2S)$ is a gas. This is due to:

$KF$ combines with $HF$ to form $KHF_2$. Which of the following species are present in this compound?

Which of the following has the highest boiling point?

Structures of molecules of two compounds are given below:
$(a)$ Which of the two compounds will have intermolecular hydrogen bonding and which compound is expected to show intramolecular hydrogen bonding.
$(b)$ The melting point of a compound depends on,among other things,the extent of hydrogen bonding. On this basis,explain which of the above two compounds will show a higher melting point.
$(c)$ Solubility of compounds in water depends on the power to form hydrogen bonds with water. Which of the above compounds will form hydrogen bonds with water easily and be more soluble in it?

The boiling point of $p$-nitrophenol is higher than that of $o$-nitrophenol because:

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