Question

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

• A. $\left[Zn\right(OH{)}_4{]}^{2-}$
• B. $Zn(OH{)}_2$
• C. Both (b) and (c)
• D. $[Zn{O}_2{]}^{2-}$

Answer 1

The correct option is C Both (b) and (c)

Zinc dissolves in excess of aqueous alkali.
$Zn+2O{H}^{-1}+2H_{2}O\to \left[Zn\right(OH{)}_4{]}^{2-}+H_2\uparrow$
Tetrahydroxozincate (II) ion
However, this reaction in $NCERT$ is given as
$Zn+2NaOH\to N{a}_{2}Zn{O}_2+H_2\uparrow$
$Zn{O}_2^{2-}$ is anhydrous form of $Zn(OH{)}_4{]}^{2-}$.
$Zn{O}_2^{2-}+2H_{2}O\rightleftharpoons \left[Zn\right(OH{)}_4{]}^{2-}$.
Hence, correct answer is (d)