Question

Which of the following will give $H_2$ gas with dilute $HN{O}_3$ ?

• A. Mg
• B. Zn
• C. Cu
• D. Hg

Answer 1

Answer: (A)

Mg, being the most reactive metal, gives $H_2$ gas with dilute $HN{O}_3$ while all other given elements react differently with dilute $HN{O}_3$ . $Mg+\underset{dilute}{2HN{O}_3}\to Mg{(N{O}_3)}_2+H_2$ $4Zn+\underset{dilute}{10HN{O}_3}\to 4Zn{(N{O}_3)}_2+N_{2}O+5H_{2}O$ $3Cu+\underset{dilute}{8HN{O}_3}\to 3Cu{(N{O}_3)}_2+2NO+4H_{2}O$ $6Hg+\underset{dilute}{8HN{O}_3}\to 3H{g}_2{(N{O}_3)}_2+2NO+4H_{2}O$