JEE Main · 2022 · 29 Jul 2022 · Shift 1 · Hydrogen

The reaction of zinc with excess of aqueous alkali, evolves hydrogen gas and gives:

Answer: (D)

Solution

Zinc is amphoteric and dissolves in excess aqueous alkali:

Zn + 2 OH^{-} + 2 H_{2} O \to [Zn (OH)_{4}]^{2 -} + H_{2}

. The zincate ion

[Zn (OH)_{4}]^{2 -}

can also be written as

[ZnO_{2}]^{2 -}

(the anhydrous form). According to NCERT notation and the official answer,

[ZnO_{2}]^{2 -}

is the accepted form.

JEE Main · 2022 · 29 Jul 2022 · Shift 1 · Single correct option