Question

Assertion :Statement $-$ 1 : $Pb{I}_4$ doesn't exist and converts into $Pb{I}_2$ and $I_2$ spontaneously at room temperature but $PbC{l}_4$ needs heating to convert into $PbC{l}_2$ and $C{l}_2$. Reason: Statement $-$ 2 : $P{b}^{2+}$ is more stable than $P{b}^{4+}$ due to inert pair effect.

• A. Statement $-$ 1 is true, Statement $-$ 2 is true and Statement $-$ 2 is correct explanation for Statement $-$ 1.
• B. Statement $-$ 1 is true, Statement $-$ 2 is true and Statement $-$ 2 is NOT the correct explanation for Statement $-$ 1.
• C. Statement $-$ 1 is true, Statement $-$ 2 is false.
• D. Statement $-$ 1 is false, Statement $-$ 2 is true.

Answer 1

The correct option is A Statement $-$ 1 is true, Statement $-$ 2 is true and Statement $-$ 2 is correct explanation for Statement $-$ 1.

The inertness of s subshell electrons towards the bond formation is called inert pair effect or it can be said as the inactiveness of electrons present in outermost shell (i.e. ns2) to get unpaired and involve in bond formation is called inert pair effect.

for example:

1) In the 13th group, thallium can exhibit +1 and+3 oxidation states but it is stable in +1 oxidation state only due to inert pair effect

2) In the 14th group, lead shows both +2 and +4 oxidation states but it is stable in +2 oxidation state due to inert pair effect.

3)In group 15 elements,(Bi) the stability of +3 oxidation state increases down the group and that of +5 oxidation state decreases down the group, due to inert pair effect.