1. 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)
Ans. (d) (i) and (iv)
Explanation: When an acid is mixed with a base; it results in neutralization
reaction.
Neutralization reaction results in formation of salt. Neutralization reaction is
exothermic reaction.
2. An aqueous solution turns red litmus solution blue. Excess addition of which
of the following solution would reverse the change?
(a) Baking powder
(b) Lime
(c) Ammonium hydroxide solution
(d) Hydrochloric acid
Ans. (d) Hydrochloric acid
Explanation: If an aqueous solution turns red litmus solution to blue, it means
that the given solution is basic. Its effect can be neutralized by an acidic
solution.
3. 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
Ans. (c) absorb moisture from the gas
4. Which of the following salts does not contain water of crystallisation?
(a) Blue vitriol
(b) Baking soda
(c) Washing soda
(d) Gypsum
Ans. (b) Baking soda
Explanation: Other salts in the options usually appear as crystalline salts, but
baking soda appears as white powder. Crystalline salts contain water of
crystallization.
5. Sodium carbonate is a basic salt because it is a salt of
(a) strong acid and strong base
(b) weak acid and weak base
(c) strong acid and weak base
(d) weak acid and strong base
Ans. (d) weak acid and strong base
Explanation: A salt of strong base and weak acid produces basic salt.
6. Calcium phosphate is present in tooth enamel. Its nature is
(a) basic
(b) acidic
(c) neutral
(d) amphoteric
Ans. (a) basic
Explanation: Phosphate ion comes from phosphoric acid; which is a strong base.
Hence, calcium phosphate is basic salt. Moreover, the fact that tooth enamel
gets damaged by acid shows that calcium phosphate is basic in nature.
7. 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
Ans. (d) An antacid
Explanation: Since soil mixture is turning the pH paper yellowish-orange, hence
soil is acidic in nature. So, adding an antacid would change the colour to
greenish-blue
8. Which of the following gives the correct increasing order of acidic strength?
(a) Water <Acetic acid <Hydrochloric acid
(b) Water <Hydrochloric acid <Acetic acid
(c) Acetic acid <Water <Hydrochloric acid
(d) Hydrochloric acid <Water <Acetic acid
Ans. (a) Water <Acetic acid <Hydrochloric acid
Explanation: Distilled water is neutral. Acetic acid is an organic acid so it is
less acidic than hydrochloric acid which is an inorganic acid.
9. If a few drops of a concentrated acid accidentally spills over the hand of a
student, what should be done?
(a) Wash the hand with saline solution
(b) Wash the hand immediately with plenty of water and apply a paste of sodium
hydrogen carbonate
(c) After washing with plenty of water apply solution of sodium hydroxide on the
hand
(d) Neutralise the acid with a strong alkali
Ans. (b) Wash the hand immediately with plenty of water and apply a paste of
sodium hydrogen carbonate
Explanation: Washing the hand with plenty of water will minimize the presence of
acid. Further, application of sodium hydrogen carbonate will neutralize any
remaining acid. Sodium hydroxide is corrosive in nature, so it should not be
used.
10. 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)
Ans. (a) (i) and (ii)
Explanation: This reaction produces carbon dioxide gas. Carbon dioxide turns
lime water milky and extinguishes a burning splinter.
11. Common salt besides being used in kitchen can also be used as the raw
material for making
(i) washing soda
(ii) bleaching powder
(iii) baking soda
(iv) slaked lime
(a) (i) and (ii)
(b) (i), (ii) and (iv),
(c) (i) and (iii)
(d) (i), (iii) and (iv)
Ans. (a) (i) and (ii)
Explanation: Slaked time is made from calcium carbonate which is not common
salt. Common salt is a raw material for making
12. One of the constituents of baking powder is sodium hydrogen carbonate, the
other constituent is
(a) hydrochloric acid
(b) tartaric acid
(c) acetic acid
(d) sulphuric acid
Ans. (b) tartaric acid
Explanation: A milk edible acid is used along with sodium hydrogen carbonate to
make baking soda. Usually, tartaric acid is used but acetic acid can also be
used.
13. 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
Ans. (c) basic
Explanation: Basic toothpaste neutralizes any acid which may be present on
teeth. Acid comes because of bacterial activity in mouth.
14. 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)
Ans. (d) (ii) and (iv)
Explanation: pH of acids is below 7 and as we go down the pH scale, acids become
stronger. When we go up the pH scale beyond 7, bases become stronger.
