Chapter - 2
Acids, Bases and Salts
( Assertion and Reasoning Questions )
Following questions consist of two statements – Assertion (A) and Reason (R).
Answer these questions selecting the appropriate option given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Q.1. Assertion (A) : The acid must always be added to water with constant stirring.
Reason (R) : Mixing of an acid with water decreases the concentration of H+ ions
per unit volume.
Q.2. Assertion (A) : Copper sulphate crystals are wet because it contains water of
crystallisation.
Reason (R) : Water of crystallisation is the fixed number of molecules of water
present in one formula unit of salt.
Q.3. Assertion (A) : The aqueous solutions of glucose and alcohol do not show
acidic character.
Reason (R) : Aqueous solutions of glucose and alcohol do not give H+ ions.
Q.4. Assertion (A) : HCl gas does not change the colour of dry blue litmus paper.
Reason (R) : HCl gas dissolves in the water present in wet litmus paper to form H+
ions.
Q.5. Assertion (A) : Weak acids have low electrical conductivity.
Reason (R) : Strong acids and weak acids have equal concentration of hydrogen
ions in their solutions.
Q.6. Assertion (A): Pure water is neither acidic nor basic.
Reason (R) : The pH of a solution is inversely proportional to the concentration of
hydrogen ions in it.
Q.7. Assertion (A) : During electrolysis of concentrated aqueous solution of sodium
chloride, hydrogen is produced at anode and chlorine gas is produced at cathode.
Reason (R) : Ions get attracted to oppositely charged electrodes.
Q.8. Assertion (A) : Baking powder is used in making cake instead of using only
baking soda.
Reason (R) : Baking powder contains tartaric acid which reacts with sodium
carbonate and removes bitter taste.
Q.9. Assertion (A) : The chemical formula of bleaching powder is CaOCI.
Reason (R) : Calcium oxide reacts with chlorine to form bleaching powder.
Q.10. Assertion (A): Plaster of Paris is stored in a moisture proof container.
Reason (R) : Plaster of Paris sets into a hard mass on wetting with water to form
anhydrous calcium sulphate.
Q.11. Assertion (A): The chemical name of bleaching powder is calcium
oxychloride.
Reason (R) : Bleaching powder is used as an oxidising agent in chemical industries.
Q.12. Assertion: The process of dissolving an acid or a base in water is highly
exothermic reaction.
Reason (R) : Water must always be added slowly to acid with constant stirring.
Q.13. Assertion (A) : Phenolphthalein is an acid-base indicator.
Reason (R) : Phenolphthalein gives different colours in acidic and basic medium.
Q.14. Assertion: Calcium sulphate hemihydrate, CaSO4.1/2 H20 is called plaster of
Paris.
Reason (R) : Plaster of Paris is used for producing moulds for pottery and ceramics
and casts of statues.
Q.15. Assertion (A) : pH = 7 signifies pure water.
Reason (R) : pH of acetic acid is greater than 7.
Q.16. Assertion (A) : HCl is a stronger acid than acetic acid.
Reason (R) : On dissociation, HCl yields lesser hydrogen ions for the same
concentration as compared to acetic acid.
Q.17. Assertion (A) : pH of ammonium nitrate solution is acidic.
Reason (R) : Solution of a salt of weak base and strong acid is acidic.
Q.18. Assertion (A) : Phosphoric acid is a weak acid.
Reason : Phosphoric acid when dissolved in water dissociates partially and
produces very little H* ions.
Q.19. Assertion (A) : Antacids neutralize the effect of extra acid produced in the
stomach during indigestion and thus provide relief.
Reason (R) : Antacids are mild bases.
Q.20. Assertion (A) : Acetic acid does not act as an acid in benzene solution.
Reason (R) : Benzene is non-polar.
Q.21. Assertion (A) : Bleaching powder reacts with dilute acids to evolve chlorine.
Reason (R) : The chlorine liberated by the action of dilute acids on bleaching
powder is called available chlorine.
Q.22. Assertion (A) : Sodium carbonate pentahydrate is also known as washing
soda.
Reason (R) : Chief raw materials for the manufacture of washing soda are NH3,
NaCl and CaCO3.
Q.23. Assertion (A) : Common salt is used for the preparation of many chemicals
such as sodium hydroxide, bleaching powder, baking soda, washing soda etc.
Reason : Main source of sodium chloride is sea water.
Q.24. Assertion (A) : AlCl3 is a basic salt.
Reason (R) : AlCl3 is a salt of strong acid and a weak base.
Q.25. Assertion (A) : Baking soda is prepared by chlor-alkali process.
Reason (R) : Brine decomposes to sodium hydroxide on passing electricity through
it.
Q.26. Assertion (A) : Salt of KNO3 is formed by strong base and weak acid.
Reason (R) : Salt of NH4Cl is formed by weak base and strong acid.
Q.27. Assertion (A) : Strength of the acid or base decreases with dilution.
Reason (R) : Ionization of an acid or a base increases with dilution.
Q.28. Assertion (A) : Higher the H ion concentration, lower is the pH value.
Reason (R) : The pH of a neutral solution=7, that of a basic solution < 7 and that of
an acidic solution > 7.
Q.29. Assertion (A) : CH3COOH is used as vinegar in cooking and food
preservatives.
Reason (R) : Strong acids are those acids which ionise almost completely in
aqueous solution and hence produce a large amount of Hions.
Q.30. Assertion (A) : Tooth decay starts when the pH of the mouth is lower than
5.5.
Reason (R) : Enamel starts corroding below 5.5 pH.
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ANSWER KEY
Q.1 : (b)
Q.2 : (d) The Assertion is false. Copper sulphate is not wet. It is an hydrated salt, as it
contains water molecules.
Q.3 : (a) Q.4 : (a) Q.5 : (c)
Q.6 : (b) Q.7 : (d) Q.8 : (a)
Q.9 : (c) Q.10 : (c) Q.11 : (b)
Q.12 : (c) The process of dissolving an acid or a base in water is highly exothermic
reaction. Acid must always be added slowly to water with constant stirring.
Q.13 : (a) Q.14 : (b)
Q.15 : (c) pH of acetic acid is less than 7.
Q.16 : (c) On dissociation, HCl yields more hydrogen ions for the same
concentration as compared to acetic acid.
Q.17 : (a) Ammonium nitrate is a salt of ammonium hydroxide (weak base) and
nitric acid (strong acid).
Q.18 : (a) Q.19 : (a).
Q.20 : (a) For ionization of an acid, polar solvents (like water) are required. As
ionization does not take place in non-polar solvents (like benzene) so acetic acid
does not acts as an acid.
Q.21 : (b) Q.22 : (d) Q.23 : (b)
Q.24 : (d) Q.25 : (d) Q.26 : (d)
Q.27 : (b) Q.28 : (c) Q.29 : (b)
Q.30 : (a)
