Question

The formation of $P{H}_4^{+}$ is difficult compared to $N{H}_4^{+}$ because :

• A. lone pair of phosphorus is optically inert
• B. lone pair of phosphorus resides in almost pure p-orbital
• C. lone pair of phosphorous resides at $s{p}^3$ orbital
• D. lone pair of phosphorus resides in almost pure s-orbital

Answer 1

The correct option is D lone pair of phosphorus resides in almost pure s-orbital

The formation of $P{H}_4^{+}$ is difficult compared to $N{H}_4^{+}$ because lone pair of phosphorus resides in almost pure s-orbital.
Due to this, phosphine lacks nucleophilicity and the donation of the lone pair to a proton becomes difficult.
In ammonia, the lone pair is present in $s{p}^3$ hybrid orbital and can be easily donated to proton.