# NEET Chemistry The p-Block Elements (XII) Questions Solved

BOARD

Account for the following ;

(i) Chlorine water loses its yellow colour on standing.

(ii) $BrC{l}_{3}$ is more stable than $BrC{l}_{5}.$

(iii) Fluorine does not form oxoacids.

(iv) $PC{l}_{5}$ acts as an oxidising agent.

(v) $S{O}_{2}$ is an air pollutant.

(i) $C{l}_{2}$ water on standing loses its yellow colour due to the formation of HCl and HOCl. HOCl is unstable and decomposes to HCl. As a result, yellow colour disappears.

$C{l}_{2}+{H}_{2}O\to HCl+HOCl$

(ii) In  can accommodate three chlorine atoms around it and hence it is stable but in $BrC{l}_{5}$, five Cl atoms cannot be accommodated around Br and hence it is unstable.

(iii) Due to high electronegativity and small size F does not form oxoacids.

(iv) In $PC{l}_{5},$ the oxidation state of phosphorus is +5. Thus, it cannot increase its oxidation state beyond +5. So $PC{l}_{5}$ cannot act as a reducing agent. However, it can decrease its oxidation state from +5 to +3 or to some lower value. Thus, it acts as an oxidising agent.

(v) $S{O}_{2}$ is a pungent and irritating gas. It acts as an air pollutant due to the following reasons :

i) It causes throat and eye irritation as it is absorbed readily by respiratory tract.

ii) It combines with moisture forming sulphurous acid. It is then converted into ${H}_{2}S{O}_{4}.$ Both these acids cause acid rain and destroy the marble, corrode metals, deteriorate fabrics, paper, leather etc.

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