Name the gas evolved when NaOH reacts with zinc.

Zinc is a transition element and it shows amphoteric nature which means that zinc can react as an acid as well as a base to form corresponding amphoteric oxides or hydroxides.

So when zinc reacts with sodium hydroxide, it forms sodium zincate and hydrogen gas is evolved. The reaction is as follows:

Zn + 2NaOH → Na₂ZnO₂ + H₂