Acid Base and Salt

NCERT Exemplar Problems

MCQs Part 2

Question 11: Common salt besides being used in kitchen can also be used as the raw material for making

  1. soda
  2. bleaching powder
  3. baking soda
  4. slaked lime
  1. (i) and (ii)
  2. (i), (ii) and (iv)
  3. (i) and (iii)
  4. (i), (iii) and (iv)
    Answer: (c) (i) and (iii)

Explanation: Soda is prepared by electrolytic decomposition of brine (NaCl solution). Baking soda is prepared by reaction between brine and ammonia. Slaked lime is made from limestone. Bleaching powder is made from chlorine (which is a byproduct of electrolytic decomposition of brine.


Question 12: One of the constituents of baking powder is sodium hydrogencarbonate, the other constituent is

  1. hydrochloric acid
  2. tartaric acid
  3. acetic acid
  4. sulphuric acid
    Answer: (b) Tartaric acid

Question 13: To protect tooth decay we are advised to brush our teeth regularly. The nature of the tooth paste commonly used is

  1. acidic
  2. neutral
  3. basic
  4. corrosive
    Answer: (c) basic

Explanation: Tooth decay happens because of action of acid on tooth enamel. The acid comes due to action of bacteria on food particles in mouth. A base helps in neutralizing the effect of acid, and thus helps in preventing tooth decay.

Question 14: Which of the following statements is correct about an aqueous solution of an acid and of a base?

  1. Higher the pH, stronger the acid
  2. Higher the pH, weaker the acid
  3. Lower the pH, stronger the base
  4. Lower the pH, weaker the base
  1. (i) and (iii)
  2. (ii) and (iii)
  3. (i) and (iv)
  4. (ii) and (iv)
    Answer: (d) (ii) and (iv)

Explanation: We know that pH of acid is less than 7, while that of base is more than 7. Increase in pH means increase in basic property.


Question 15: The pH of the gastric juices released during digestion is

  1. less than 7
  2. more than 7
  3. equal to 7
  4. equal to 0
    Answer: (a) less than 7

Explanation: pH of any acid is always less than 7

Question 16: Which of the following phenomena occur, when a small amount of acid is added to water?

  1. Ionisation
  2. Neutralisation
  3. Dilution
  4. Salt formation
  1. (i) and (ii)
  2. (i) and (iii)
  3. (ii) and (iii)
  4. (ii) and (iv)
    Answer: (b) (i) and (iii)

Explanation: Whenever an acid is dissolved in water, the acid dissociates into ions. Moreover, dissolution in water results in dilution of acid. Neutralisation and salt formation are more or less similar because neutralization is the process and salt formation is the result of this process. But neutralization happens when an acid reacts with a base.

Question 17: Which one of the following can be used as an acid–base indicator by a visually impaired student?

  1. Litmus
  2. Turmeric
  3. Vanilla essence
  4. Petunia leaves
    Answer: (c) Vanilla essence

Explanation: Vanilla essence will show change in smell in presence of acid/base. A visually impaired student cannot perceive change in colour but can easily detect change in smell.


Question 18: Which of the following substance will not give carbon dioxide on treatment with dilute acid?

  1. Marble
  2. Limestone
  3. Baking soda
  4. Lime
    Answer: (d) Lime

Explanation: Lime is calcium hydroxide, which means carbon is not present in this compound. Marble and limestone are calcium carbonate, while baking soda is sodium bicarbonate. In other words, carbon is present in these three compounds. And we cannot make carbon dioxide without carbon.

Question 19: Which of the following is acidic in nature?

  1. Lime juice
  2. Human blood
  3. Lime water
  4. Antacid
    Answer: (a) Lime juice

Question 20: In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus (Given Figure) was set up. Which among the following statement(s) is(are) correct?

set up for electrolysis
  1. Bulb will not glow because electrolyte is not acidic
  2. Bulb will glow because NaOH is a strong base and furnishes ions for conduction
  3. Bulb will not glow because circuit is incomplete
  4. Bulb will not glow because it depends upon the type of electrolytic solution
  1. (i) and (iii)
  2. (ii) and (iv)
  3. (ii) only
  4. (iv) only
    Answer: (c) (ii) only

Explanation: Acid, base and even salt can be used for making electrolyte solution.



Copyright © excellup 2014