Acid, Base & Salt

MCQs: 1

Question: 1. What is the taste of acid?

(a) Sweet

(b) Sour

(c) Salty

(d) Bitter

Answer: (b) Sour

Explanation: All acid tastes sour.

Question: 2. What is the taste of a base?

(a) Sweet

(b) Sour

(c) Salty

(d) Bitter

Answer: (d) Bitter

Explanation: All base taste bitter.

Question: 3. How does a base solution feel in touch?

(a) Hard

(b) Soft

(c) Soapy

(d) Sharp

Answer: (c) Soapy

Explanation: Solutions of all bases feel soapy

Question: 4: What happens when a blue litmus paper is dipped into an acid solution?

(a)Litmus paper turns red

(b) Litmus paper turns green

(c) Colour of litmus paper vanishes out

(d) No change in the colour of litmus paper

Answer: (a) Litmus paper turns red

Explanation: An acid solution turns blue litmus paper red.

Question: 5: What happens when a blue litmus paper is dipped into a base solution?

(a) Litmus paper turns red

(b) Litmus paper turns green

(c) Colour of litmus paper vanishes out

(d) No change in the colour of litmus paper

Answer: (d) No change in the colour of litmus paper

Explanation: Solution of base turns red litmus paper blue therefore no change takes place in the colour of blue litmus paper.

Question: 6. What happens when a dry blue litmus paper is touched to acid powder?

(a) Litmus paper turns red

(b) Litmus paper turns green

(c) Colour of litmus paper vanishes out

(d) No change in the colour of litmus paper

Answer: (d) No change in the colour of litmus paper

Explanation: Acid powder does not change the colour of litmus paper. If blue litmus paper is dipped in the aqueous solution of acid then only blue litmus paper turns red. Water is necessary to change the colour of litmus paper because acid dissociates hydrogen ions in aqueous solution.

Question: 7. What happens when a dry red litmus paper is touched to base powder?

(a) Litmus paper turns red

(b) Litmus paper turns green

(c) Colour of litmus paper vanishes out

(d) No change in the colour of litmus paper

Answer: (d) No change in the colour of litmus paper

Explanation: A base dissociates hydroxide ions in their aqueous solution and changes the red litmus paper to blue. Therefore, base powder does not change the colour of dry red litmus paper.

Question: 8. What happens when a moist blue litmus paper is brought near the hydrochloric acid gas?

(a) Litmus paper turns red

(b) Litmus paper turns green

(c) Colour of litmus paper vanishes out

(d) No change in the colour of litmus paper

Answer: (a) Litmus paper turns red

Explanation: It is necessary to moist the litmus paper to detect the acidic gas. Dry litmus paper does not change the colour when brought near the hydrochloric acid gas. An acid does not dissociate hydrogen ions without water.

Question: 9: What happens when a red litmus paper is dipped into a base solution?

(a) Litmus paper turns blue

(b) Litmus paper turns green

(c) Colour of litmus paper vanishes out

(d) No change in the colour of litmus paper

Answer: (a) Litmus paper turns blue

Explanation: All bases turn red litmus paper into blue.

Question: 10: What happens when a red litmus paper is dipped into an acid solution?

(a) Litmus paper turns blue

(b) Litmus paper turns green

(c) Colour of litmus paper vanishes out

(d) No change in the colour of litmus paper

Answer: (d) No change in the colour of litmus paper

Explanation: Acid solution changes the colour of blue litmus paper to red. Thus, red litmus remains blue.