NEET 2022 — Chemistry solution

NEET2022Chemistry

Identify the incorrect statement from the following

A
The oxidation number of K in KO $_{2}$ is + 4.
B
Ionisation enthalpy of alkali metals decreases from top to bottom in the group.
C
Lithium is the strongest reducing agent among the alkali metals.
D
Alkali metals react with water to form their hydroxides.

Solution

Potassium superoxide KO $_{2}$ contains the superoxide ion O $_{2}^{-}$ (overall charge $- 1$ ). To balance, K must carry an oxidation state of $+ 1$ , not $+ 4$ .

Statement (1) is therefore incorrect.

The other statements are correct: ionisation enthalpy of alkali metals decreases down the group, lithium is the strongest reducing agent in aqueous solution (because of its very high hydration enthalpy), and alkali metals react vigorously with water to yield hydroxides and H $_{2}$ .

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