pBlock ElementsII - Result Question 60
####55. Statement I Although $PF _5, PCl _5$ and $PBr _5$ 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 $KClO _3$ in presence of catalytic amount of $MnO _2$, a gas $W$ is formed. Excess amount of $W$ reacts with white phosphorus to give $X$. The reaction of $X$ with pure $HNO _3$ 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 ( $N X _3$ with eight electrons in valence shell of $N$ ).
Phosphorus has vacant $3 d$-orbitals, it can expand its valence shell beyond eight electrons, its both trihalides and pentahalides exist.
Passage
$$ \begin{aligned} & KClO _3 \xrightarrow[\Delta]{MnO _2} KCl+\underset{W}{O _2} \ & O _2+P _4 \stackrel{\Delta}{\longrightarrow} P _4 O _{10} \xrightarrow{HNO _3} N _2 O _5+HPO _3 \end{aligned} $$
