Question

Hydrogen is not obtained when Zn reacts with:

• A. cold water
• B. hot $NaOH$
• C. dil. $H_{2}S{O}_4$
• D. dil. $HCl$

Answer 1

The correct option is A cold water

Zinc is a low reactive metal which does not react with cold water and hence no gas is evolved.

$Zn+H_{2}O\to$No reaction

However, Zn reacts with dil. $HCl$, dil. $H_S{O}_4$ and Hot $NaOH$ according to the following reactions

$Zn+2HCl\to ZnC{l}_2+H_2$

$Zn+H_{2}S{O}_4\to ZnS{O}_4+H_2$

$Zn+2NaOH\to N{a}_{2}Zn{O}_2+H_2$