Question

A certain aqueous solution turns blue litmus red. On adding an excess of which of the following solutions will this change be reversed?
Lemon juice
Magnesium hydroxide
Vinegar
Calcium sulphate

Hint:

Acids turn blue litmus red, and bases (alkalies) like magnesium hydroxide reverse this.

Answer 1

The given solution is acidic because it turns blue litmus red. To reverse this, a basic solution is needed.
Correct option: (2) Magnesium hydroxide — It is a strong base and will neutralize the acid.