Question

The metal that gives hydrogen gas upon treatment with both acid as well as base is :

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> JEE MAIN 2019

Answer 1

Generally, metals react with acids and produce hydrogen gas but the metals do not react with bases and give off hydrogen gas.
Zinc and aluminium are the exceptions in this case. Both of them can react with acid and with base such metals are known as amphoteric metals.
Amphoteric metals are those that can react both as an acid and as a base. Many metals such as zinc, copper. Aluminium forms amphoteric oxides or hydroxides.
For zinc .
(A).Zinc can react with strong acid such as $HCl$ to give off $H_2$. The reaction can be written as :
$Zn+2HCl\to ZnC{l}_2+H_2$
(B). The reaction of zinc $\left(Zn\right)$ with a base $NaOH$ also produces hydrogen.
The reaction is :
$Zn+2NaOH\to N{a}_{2}Zn{O}_2+H_2$
Option (a) is correct