Statement I:- Hydrogen gas is not evolved when zinc reacts with cold water.
Statement II:- Sodium reacts vigorously with cold water to produce sodium hydroxide and hydrogen gas.
Zinc does not react with cold water to produce hydrogen gas. It produces hydrogen gas on reacting with steam. The reaction involved is:
Zn(s) + 2H2O(l) → Zn(OH)2(aq) +H2(g)
Sodium reacts vigorously with cold water to produce sodium hydroxide and hydrogen gas. The reaction involved is:
2Na(s) + 2H2O(l) → 2NaOH(aq) +H2(g)