The correct option is Sodium zincate.
Explanation
Metals generally react with acids to form salts and release hydrogen gas. However, certain metals such as zinc and aluminium are amphoteric in nature, meaning they can react with both acids and strong bases (alkalis). When these metals react with a strong base like sodium hydroxide, they form a soluble salt and evolve hydrogen gas.
Detailed Analysis:
- Reaction with Sodium Hydroxide: When zinc granules are heated with a sodium hydroxide ($NaOH$) solution, a chemical reaction occurs forming sodium zincate ($Na_2ZnO_2$) and hydrogen gas ($H_2$).
The chemical equation is:
Zn + 2NaOH → Na2ZnO2 (Sodium zincate) + H2 - Incorrect Options:
- Zinc sulphate ($ZnSO_4$): Formed when zinc reacts with sulphuric acid ($H_2SO_4$).
- Zinc chloride ($ZnCl_2$): Formed when zinc reacts with hydrochloric acid ($HCl$).
- Zinc nitrate ($Zn(NO_3)_2$): Formed when zinc reacts with nitric acid ($HNO_3$).
Key Takeaway:
Zinc is an amphoteric metal that reacts with strong bases like sodium hydroxide to produce sodium zincate and hydrogen gas, unlike most metals which do not react with bases.