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Question
The aqueous solution of one of the following salts will turn red litmus to blue. This salt is:
(a) potassium sulphate
(b) sodium sulphate
(c) sodium chloride
(d) potassium carbonate
Solution
potassium carbonate
Potassium carbonate (K2CO3) is formed from a weak acid, carbonic acid (H2CO3), and a strong base, potassium hydroxide (KOH). On hydrolysis, K2CO3 forms more OH- ions than H+ ions. Thus, it is basic and therefore turns red litmus blue.
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