Solved: CHEMISTRY Question for NEET

NEET CHEMISTRYMedium

For the reaction $PbO_2 \rightarrow PbO$ , $\Delta G_{298} < 0$ , and for the reaction $SnO_2 \rightarrow SnO$ , $\Delta G_{298} > 0$ . The most probable oxidation states of Pb and Sn will be respectively:

$Pb^{4+}, Sn^{4+}$

$Pb^{4+}, Sn^{2+}$

$Pb^{2+}, Sn^{2+}$

$Pb^{2+}, Sn^{4+}$

Step-by-Step Solution

The given $\Delta G$ values indicate the spontaneity of the decomposition reactions.

Lead (Pb): The reaction $PbO_2 (+4) \rightarrow PbO (+2)$ has $\Delta G < 0$ , meaning it is spontaneous. This indicates that the +2 oxidation state is thermodynamically more stable than the +4 state for Lead. This is due to the inert pair effect, where the $6s^2$ electrons are reluctant to participate in bonding.
Tin (Sn): The reaction $SnO_2 (+4) \rightarrow SnO (+2)$ has $\Delta G > 0$ , meaning it is non-spontaneous. This indicates that the +4 oxidation state is more stable than the +2 state for Tin.

Thus, the most characteristic states are Pb(+2) and Sn(+4).

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