pBlock ElementsII 1 Question 60
55. Statement I Although $\mathrm{PF}{5}, \mathrm{PCl}{5}$ and $\mathrm{PBr}_{5}$ are known, the pentahalides of nitrogen have not been observed.
Statement II Phosphorus has lower electronegativity than nitrogen.
(1994, 2M)
Passage Based Questions
Passage
Upon heating $\mathrm{KClO}{3}$ in presence of catalytic amount of $\mathrm{MnO}{2}$, a gas $W$ is formed. Excess amount of $W$ reacts with white phosphorus to give $X$. The reaction of $X$ with pure $\mathrm{HNO}_{3}$ gives $Y$ and $Z$.
(2017 Adv.)
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Solution:
- Both Statement I and Statement II are independently correct but reason is not the correct explanation of Statement I. Nitrogen does not has any vacant $d$-orbitals, it cannot expand its valence shell beyond eight electrons, i.e. it cannot violate octet. Therefore, nitrogen forms only trihalides ( $\mathrm{N} X_{3}$ with eight electrons in valence shell of $\mathrm{N}$ ).
Phosphorus has vacant $3 d$-orbitals, it can expand its valence shell beyond eight electrons, its both trihalides and pentahalides exist.
Passage
$$ \begin{aligned} & \mathrm{KClO}{3} \xrightarrow[\Delta]{\mathrm{MnO}{2}} \mathrm{KCl}+\underset{W}{\mathrm{O}{2}} \ & \mathrm{O}{2}+\mathrm{P}{4} \stackrel{\Delta}{\longrightarrow} \mathrm{P}{4} \mathrm{O}{10} \xrightarrow{\mathrm{HNO}{3}} \mathrm{~N}{2} \mathrm{O}{5}+\mathrm{HPO}_{3} \end{aligned} $$
