Question

Which of the following combination will produce $H_2$ gas?

• A. $Fe$ metal and conc. $HNO_3$
• B. $Cu$ metal and conc. $HNO_3$
• C. $Zn$ metal and $NaOH_{(aq)}$
• D. $Au$ metal and $NaCN_{(aq)}$ in the presence of air

Answer 1

Answer: (C)

$Zn$ metal and $NaOH_{(aq)}$

Answer 2

$Zn +2 NaOH \longrightarrow Na _{2} ZnO _{2}+ H _{2} \uparrow$