NEET 2026 (Phase 1) · ChemistryPrevious Year Question
Identify the incorrect statement from the following:
- A.(a) Alkali metals react with water to form their hydroxides
- B.(b) The oxidation number of K in \ce{KO2} is $+4$✓
- C.(c) Ionisation enthalpy of alkali metals decreases from top to bottom in the group
- D.(d) Lithium is the strongest reducing agent among the alkali metals
Correct Answer
(B) (b) The oxidation number of K in \ce{KO2} is $+4$
Solution & Explanation
\textbf{Answer:} (b) The oxidation number of K in \ce{KO2} is $+4$ \textbf{Solution:} The oxidation number of K in \ce{KO2} (potassium superoxide) is not $+4$; potassium is always $+1$. The superoxide ion \ce{O2^-} carries an overall $-1$ charge, so each O is $-1/2$ and K is $+1$. Statements (a), (c) and (d) are correct properties of alkali metals. Hence statement (b) is the incorrect one.
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