When sodium hydroxide solution is added to a solution of zinc salt, the white precipitate formed re-dissolves in excess sodium hydroxide because
- sodium is more reactive than zinc
- sodium hydroxide is a strong alkali
-
zinc hydroxide is amphoteric
- zinc hydroxide is unstable
The correct answer is: C
Explanation
Sodium hydroxide is a strong base that can react with certain salts, especially those that contain amphoteric metals. Zinc is an amphoteric metal, meaning it can react with both acids and bases. Like the hydroxides of other metals, such as lead, aluminium, beryllium, tin and chromium, zinc hydroxide (and zinc oxide), is amphoteric. Thus it will dissolve readily in a dilute solution of a strong acid, such as HCl, and also in a solution of an alkali such as sodium hydroxide. The correct answer in option C