Question

Phosphorus cannot form $PH_5$ with its outer electronic configuration as $3s^23p^3$ because

• A. phosphorus cannot show $+5$ oxidation state
• B. $PH_5$ is not a stable compound
• C. $\Delta_aH$ value of dihydrogen and $\Delta_{eg}H$ value of hydrogen do not favour higher oxidation state of phosphorus
• D. phosphorus is not very reactive hence does not form $PH_5$

Answer 1

Answer: (C)

$\Delta_aH$ value of dihydrogen and $\Delta_{eg}H$ value of hydrogen do not favour higher oxidation state of phosphorus

Answer 2

Since higher oxidation state of $P$ is not favoured by high $\Delta_aH$ of dihydrogen and $\Delta_{eg}H$ of hydrogen, $P$ does not form $PH_5$ though it exhibits $+3$ and $+5$ oxidation states.