ACID AND BASE

What happens when a solution of an acid is mixed with a solution of a base in a test tube?

(i) The temperature of the solution increases

(ii) The temperature of the solution decreases

(iii) The temperature of the solution remains the same

(iv) Salt formation takes place

• (a) (i) only

• (b) (i) and (iii)

• (c) (ii) and (iii)

• (d) (i) and (iv)

During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to

(a) absorb the evolved gas

(b) moisten the gas

(c) absorb moisture from the gas

(d) absorb Cl– ions from the evolved gas

• a

• b

• c

• d

Which of the following salts does not contain water of crystallisation?

(a) Blue vitriol

(b) Baking soda

(c) Washing soda

(d) Gypsum

• a

• b

• c

• d

Calcium phosphate is present in tooth enamel. Its nature is

(a) basic

(b) acidic

(c) neutral

(d) amphoteric

• a

• b

• c

• d

A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the colour of this pH paper to greenish-blue?

(a) Lemon juice

(b) Vinegar

(c) Common salt

(d) An antacid

• a

• b

• c

• d

Sodium hydrogencarbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved?

(i) It turns lime water milky

(ii) It extinguishes a burning splinter

(iii) It dissolves in a solution of sodium hydroxide

(iv) It has a pungent odour

• (a) (i) and (ii)

• (b) (i), (ii) and (iii)

• (c) (ii), (iii) and (iv)

• (d) (i) and (iv)

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

(a) hydrochloric acid

(b) tartaric acid

(c) acetic acid

(d) sulphuric acid

• a

• b

• c

• d

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

(a) acidic

(b) neutral

(c) basic

(d) corrosive

• a

• b

• c

• d

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

(i) Higher the pH, stronger the acid

(ii) Higher the pH, weaker the acid

(iii) Lower the pH, stronger the base

(iv) Lower the pH, weaker the base

• (a) (i) and (iii)

• (b) (ii) and (iii)

• (c) (i) and (iv)

• (d) (ii) and (iv)

The pH of the gastric juices released during digestion is

(a) less than 7

(b) more than 7

(c) equal to 7

(d) equal to 0

• a

• b

• c

• d