Question

Assertion :$P_4$ exists but $N_4$ does not; $N_2$ exists but $P_2$ does not. Reason: white phosphorus : $P_4$ $N\equiv N946kJmo{l}^{-1},P\equiv P481kJmo{l}^{-1},N-N160kJmo{l}^{-1},P-P215kJmo{l}^{-1}$Greater the B.E., greater the stability [compare BE of $N\equiv N$ and $N-N$ (in $N_4$) and $P-P$ (in $P_4$)]

Read the above assertion and reason and choose the correct option regarding it.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Due to larger atomic size P is unable to form pi bonds and so it is tetra-atomic in which each Patom is linked with 3 other P atoms by 3 sigma bond. But, due to smaller atomic size N forms 1 sigma and 2 pi bonds i.e. triple bonds with other N atom and exists as diatomic molecule.