Consider the following reactions. PbCl₂ + K₂CrO₄ arrow A + 2KCl$PbCl_{2} + K_{2}CrO_{4} \rightarrow A + 2KCl$ (Hot solution) A + NaOH leftharpoons B + Na₂CrO₄$A + NaOH \rightleftharpoons B + Na_{2}CrO_{4}$ PbSO₄ + 4CH₃COONH₄ arrow (NH₄)₂SO₄ + X$PbSO_{4} + 4CH_{3}COONH_{4} \rightarrow (NH_{4})_{2}SO_{4} + X$ In the above reactions, A, B and X are respectively

Core Logic

Statement I: S₈$S_8$ disproportionates in alkaline medium to give sulphide (S²⁻$S^{2-}$) and thiosulphate (S₂O₃²⁻$S_2O_3^{2-}$). The reaction is:

This is a correct statement.

Statement II: ClO₄^-$ClO_4^-$ contains chlorine in its highest possible oxidation state of +7$+7$. A species can undergo disproportionation only if the element can exist in both higher and lower oxidation states than the present one. Since chlorine cannot exceed +7$+7$, ClO₄^-$ClO_4^-$ cannot undergo disproportionation. This is an incorrect statement.

Step 1: Final Conclusion

Statement I is correct, and Statement II is incorrect. Therefore, option (1) is the correct answer.

Chapter Mix

Class 11 Chemistry: Redox Reactions Class 12 Chemistry: The p-Block Elements

Core Logic

Statement I and II are False.

Noble gases have low boiling points. Noble gases are held together by weak dispersion forces.

Pattern Recognition

Noble gases are characterized by extremely weak intermolecular forces (London dispersion forces) because they are monoatomic and non-polar, which directly results in very low boiling and melting points.

Chapter Mix

Class 12 Chemistry: The p-Block Elements

Core Logic

In Group 14 elements, the nature of oxides varies down the group: CO$CO$ is neutral. CO₂$CO_2$ and SiO₂$SiO_2$ are acidic. GeO₂$GeO_2$ is distinctly acidic. SnO₂$SnO_2$ and PbO₂$PbO_2$ are amphoteric.

Pattern Recognition

Tin (Sn$Sn$) and Lead (Pb$Pb$) mostly form amphoteric oxides (e.g., SnO, SnO₂, PbO, PbO₂$SnO, SnO_2, PbO, PbO_2$), distinguishing them from the acidic oxides of Carbon and Silicon.

Chapter Mix

Class 11 Chemistry: The p-Block Elements