Question

Sodium hydroxide is added drop by drop to the solution of metallic salts because:

• A. Metallic hydroxides precipitated are identified by their distinct colour.
• B. Difficult to identify colour of precipitate.
• C. Alkali must be added quickly to the solution of metallic salts.
• D. It is easy to miss a precipitate.

Answer 1

The correct option is A

Metallic hydroxides precipitated are identified by their distinct colour.

When sodium hydroxide solution is added drop by drop to the solution of metallic salts, the metal hydroxide formed gets precipitated. Formation and colour of the precipitate identifies the metal ion. Some precipitated metallic hydroxides dissolve in excess of sodium hydroxide solution to give soluble complexes. If sodium hydroxide is added quickly to the solution, its easy to miss the precipitate that dissolve in excess.