Q.Group 14 elements show two characteristic oxidation states, $+2$ and $+4$. State which is more stable for carbon and silicon, which becomes more stable for tin and lead, and explain the trend using the inert pair effect.

[!TLDR] +4 is more stable for C and Si; +2 becomes progressively more stable down the group and is the more stable state for Pb, due to the strengthening inert pair effect. [!ANSWER] Carbon and silicon strongly favour $+4$; the inert-pair-stabilised $+2$ state becomes competitive at tin …

Group 14 elements can in principle show both the group oxidation state $+4$ (using all four valence electrons, $ns^2np^2$) and the inert-pair state $+2$ (using only the two $np$ electrons and leaving the $ns^2$ pair non-bonding). For carbon and silicon, $+4$ is overwhelmingly the more stable and dominant state — essentially the whole of organic chemistry (carbon) and silicate/silica chemistry (silicon) is built on the $+4$ state, with $+2$ species being comparatively unusual and reactive (carbon monoxide, loosely regarded as $\text{C}^{2+}$-like, is a notable but reactive/reducing exception). Moving down the group, the inert pair effect — the increasingly tight, poorly-shielded holding of the outer $ns^2$ pair, reinforced by relativistic contraction for the heaviest elements — becomes steadily more significant: by germanium and especially tin, both $+2$ and $+4$ compounds are reasonably well known and comparably stable. By lead, the effect has become dominant: $\text{Pb}^{2+}$ (as in the common, stable compound $\text{PbO}$) is now more stable than $\text{Pb}^{4+}$, so that $\text{PbO}_2$, the lead(IV) oxide, be …

State the two Group 14 oxidation states (+4 group state, +2 inert-pair state), then trace how their relative stability shifts down the group due to the strength …

Assuming +4 remains the more stable state throughout the whole group including lead; forgetting to connect the trend explic …