(b) Sodium zincate
Zinc reacts with sodium hydroxide to form sodium zincate (Na₂ZnO₂) and hydrogen gas, as zinc is amphoteric and reacts with bases.
Zinc is an amphoteric metal — it reacts with both acids and bases. With NaOH, it forms sodium zincate (Na₂ZnO₂), not zinc oxide or zinc hydroxide. The NCERT chapter on metals mentions zinc oxide as an amphoteric oxide, which is the key concept behind this reaction. Remember: amphoteric metals/oxides react with bases to form zincate/aluminate salts.