Question

Litmus paper is made from water-soluble dyes which are extracted from lichens. This paper is used as an acid-base indicator. Which of these common household substances would turn blue litmus paper red? A) ammonia B) vinegar C) baking soda D) distilled water

Answer 1

The answer is B- Vinegar.

Answer 2

Answer: B) vinegar

Explanation: Acids are those substances which when dissolved in water give $H^+$ ions. They turn blue litmus red.

Bases are those substances which when dissolved in water give $OH^-$ ions. They turn red litmus blue.

Ammonia is a base which when dissolved in water forms ammonium hydroxide and gives $OH^-$ ions and turns red litmus blue.

$NH_4OH\rightarrow NH_4^++OH^-$

Vinegar is acetic acid and thus gives $H^+$ ions and turn blue litmus red.

$CH_3COOH\rightarrow CH_3COO^-+H^+$

Baking soda is a basic salt $NaHCO_3$ which turns red litmus blue.

Distilled water $H_2O$ is neutral which shows no color change with red or blue litmus.