NCERT MCQs of class 10 General Science Chapter no 2 Acids, Bases and Salts

1) Which of the following is an acid?

(a) Sodium hydroxide
(b) Hydrochloric acid
(c) Potassium hydroxide
(d) Calcium hydroxide
Answer: (b) Hydrochloric acid
Explanation: Hydrochloric acid (HCl) is an acid, while the others are bases.

2) What is the taste of acids?

(a) Bitter
(b) Sweet
(c) Sour
(d) Salty
Answer: (c) Sour
Explanation: Acids have a characteristic sour taste, like lemon juice or vinegar.

3) Which ion is responsible for the acidic nature of a substance?

(a) Hydroxide ion (OH−)
(b) Hydrogen ion (H+)
(c) Sodium ion (Na+)
(d) Chloride ion (Cl−)
Answer: (b) Hydrogen ion (H+)
Explanation: The release of H+ ions in aqueous solution makes a substance acidic.

4) Which base is commonly used in the manufacture of soaps?

(a) Sodium hydroxide
(b) Calcium hydroxide
(c) Magnesium hydroxide
(d) Potassium hydroxide
Answer: (a) Sodium hydroxide
Explanation: Sodium hydroxide (NaOH), also known as caustic soda, is used in soap manufacturing.

5) What is the pH of pure water?

(a) 0
(b) 7
(c) 14
(d) 1
Answer: (b) 7
Explanation: Pure water is neutral and has a pH of 7.

6) A substance with a pH less than 7 is:

(a) Neutral
(b) Acidic
(c) Basic
(d) None of the above
Answer: (b) Acidic
Explanation: Substances with a pH below 7 are classified as acidic.

7) Which of the following is a weak acid?

(a) Hydrochloric acid
(b) Sulfuric acid
(c) Acetic acid
(d) Nitric acid
Answer: (c) Acetic acid
Explanation: Acetic acid (CH3COOH) is a weak acid as it partially ionizes in water.

8) What is the pH range of the human stomach?

(a) 1–3
(b) 4–5
(c) 7
(d) 10–12
Answer: (a) 1–3
Explanation: The stomach produces hydrochloric acid, creating a highly acidic environment with a pH of 1–3.

9) Which of the following indicators turns red in an acidic solution?

(a) Phenolphthalein
(b) Methyl orange
(c) Litmus
(d) Both (b) and (c)
Answer: (d) Both (b) and (c)
Explanation: Methyl orange and litmus paper turn red in acidic solutions.

10) Which of the following is not an alkali?

(a) Sodium hydroxide
(b) Calcium hydroxide
(c) Ammonium hydroxide
(d) Glucose
Answer: (d) Glucose
Explanation: Glucose is not a base or an alkali; it is a sugar.

11) What is formed when an acid reacts with a metal?

(a) Hydrogen gas and a salt
(b) Water and a salt
(c) Carbon dioxide and a salt
(d) Oxygen gas and a salt
Answer: (a) Hydrogen gas and a salt
Explanation: Acids react with metals to produce hydrogen gas and a salt.

12) What is the chemical formula of baking soda?

(a) Na2CO3
(b) NaHCO3
(c) CaCO3
(d) NaOH
Answer: (b) NaHCO3
Explanation: Baking soda is sodium bicarbonate (NaHCO3).

13) What type of salt is formed when hydrochloric acid reacts with sodium hydroxide?

(a) Acidic salt
(b) Basic salt
(c) Neutral salt
(d) None of the above
Answer: (c) Neutral salt
Explanation: The reaction between HCl and NaOH forms sodium chloride, a neutral salt.

14) Which of the following is a basic oxide?

(a) SO2
(b) CO2
(c) CaO
(d) N2O5
Answer: (c) CaO
Explanation: Calcium oxide (CaO) is a basic oxide, reacting with water to form a base.

15) Which gas is evolved when dilute sulfuric acid reacts with zinc?

(a) Oxygen
(b) Hydrogen
(c) Carbon dioxide
(d) Sulfur dioxide
Answer: (b) Hydrogen
Explanation: Zinc reacts with sulfuric acid to release hydrogen gas: Zn+H2SO4→ZnSO4+H2

16) Which acid is found in vinegar?

(a) Lactic acid
(b) Acetic acid
(c) Citric acid
(d) Tartaric acid
Answer: (b) Acetic acid
Explanation: Vinegar contains acetic acid (CH3COOH).

17) Which indicator is colorless in an acidic solution and pink in a basic solution?

(a) Methyl orange
(b) Litmus
(c) Phenolphthalein
(d) Universal indicator
Answer: (c) Phenolphthalein
Explanation: Phenolphthalein is colorless in acids and turns pink in bases.

18) Which base is used in antacids to neutralize stomach acid?

(a) Sodium hydroxide
(b) Magnesium hydroxide
(c) Potassium hydroxide
(d) Calcium hydroxide
Answer: (b) Magnesium hydroxide
Explanation: Magnesium hydroxide, also called milk of magnesia, neutralizes excess stomach acid.

19) What is the common name of Ca(OH)2?

(a) Limewater
(b) Quicklime
(c) Slaked lime
(d) Bleaching powder
Answer: (c) Slaked lime
Explanation: Ca(OH)2 is commonly known as slaked lime.

20) Which of the following salts is used in fire extinguishers?

(a) Sodium carbonate
(b) Sodium bicarbonate
(c) Calcium carbonate
(d) Magnesium sulfate
Answer: (b) Sodium bicarbonate
Explanation: Sodium bicarbonate (NaHCO3) is used in fire extinguishers as it releases CO2 when heated.

21) Which acid is commonly found in citrus fruits?
- (a) Acetic acid
- (b) Citric acid
- (c) Tartaric acid
- (d) Lactic acid
  Answer: (b) Citric acid
  Explanation: Citrus fruits like oranges and lemons contain citric acid.

22) What is the pH of a neutral solution?

(a) 0
(b) 7
(c) 14
(d) 10
Answer: (b) 7
Explanation: A neutral solution, like pure water, has a pH of exactly 7.

23) Which of the following is a strong acid?

(a) Acetic acid
(b) Hydrochloric acid
(c) Carbonic acid
(d) Citric acid
Answer: (b) Hydrochloric acid
Explanation: Hydrochloric acid (HCl) completely ionizes in water, making it a strong acid.

24) What is formed when carbon dioxide is passed through limewater?

(a) Calcium carbonate
(b) Calcium hydroxide
(c) Sodium carbonate
(d) Calcium oxide
Answer: (a) Calcium carbonate
Explanation: Limewater (Ca(OH)2 reacts with carbon dioxide (CO2CO_2CO2) to form calcium carbonate (CaCO3), turning the solution milky.

25) Which acid is found in the sting of ants?

(a) Acetic acid
(b) Formic acid
(c) Lactic acid
(d) Tartaric acid
Answer: (b) Formic acid
Explanation: The sting of ants contains formic acid, causing irritation and pain.

26) Which of the following indicators is natural?

(a) Litmus
(b) Phenolphthalein
(c) Methyl orange
(d) Universal indicator
Answer: (a) Litmus
Explanation: Litmus is a natural indicator obtained from lichens.

27) Which base is found in household bleach?

(a) Sodium hydroxide
(b) Potassium hydroxide
(c) Sodium hypochlorite
(d) Magnesium hydroxide
Answer: (c) Sodium hypochlorite
Explanation: Sodium hypochlorite (NaOCl) is the active ingredient in household bleach.

28) What is the color of methyl orange in a basic solution?

(a) Red
(b) Yellow
(c) Pink
(d) Blue
Answer: (b) Yellow
Explanation: Methyl orange turns yellow in basic solutions.

29) Which of the following is a neutral salt?

(a) Sodium chloride
(b) Ammonium chloride
(c) Sodium bicarbonate
(d) Calcium carbonate
Answer: (a) Sodium chloride
Explanation: Sodium chloride (NaCl) is neutral as it results from a strong acid and a strong base.

30) What is the chemical formula for plaster of Paris?

(a) CaSO4⋅2H2O
(b) CaSO4⋅1/2H2O
(c) CaCO3
(d) Ca(OH)2
Answer: (b) CaSO4⋅1/2H2O
Explanation: Plaster of Paris is calcium sulfate hemihydrate.

31) What is the pH range of acidic substances?

(a) 0–7
(b) 7–14
(c) Exactly 7
(d) 1–14
Answer: (a) 0–7
Explanation: Acidic substances have a pH below 7.

32) Which of the following is amphoteric?

(a) Al2O3
(b) CaO
(c) SO2S
(d) CO2
Answer: (a) Al2O3A
Explanation: Amphoteric oxides, like Al2O3, react with both acids and bases.

33) Which compound is commonly known as washing soda?

(a) Sodium bicarbonate
(b) Sodium carbonate
(c) Calcium carbonate
(d) Magnesium sulfate
Answer: (b) Sodium carbonate
Explanation: Washing soda is sodium carbonate (Na2CO3).

34) Which acid is used in car batteries?

(a) Nitric acid
(b) Sulfuric acid
(c) Hydrochloric acid
(d) Acetic acid
Answer: (b) Sulfuric acid
Explanation: Sulfuric acid (H2SO4) is used as an electrolyte in car batteries.

35) What happens to the pH of a solution when an acid is added to it?

(a) Increases
(b) Decreases
(c) Remains constant
(d) Becomes neutral
Answer: (b) Decreases
Explanation: Adding an acid increases the concentration of H+, lowering the pH.

36) Which salt is used in the preparation of glass?

(a) Sodium chloride
(b) Sodium carbonate
(c) Sodium sulfate
(d) Potassium nitrate
Answer: (b) Sodium carbonate
Explanation: Sodium carbonate (Na2CO3) is used in the manufacture of glass.

37) What is the color of phenolphthalein in a neutral solution?

(a) Pink
(b) Red
(c) Colorless
(d) Yellow
Answer: (c) Colorless
Explanation: Phenolphthalein remains colorless in neutral solutions.

38) Which substance is used to treat acidic soils?

(a) Limewater
(b) Slaked lime
(c) Gypsum
(d) Sodium chloride
Answer: (b) Slaked lime
Explanation: Slaked lime (Ca(OH)2) neutralizes acidic soils.

39) Which of the following is an example of an alkaline earth metal?

(a) Sodium
(b) Magnesium
(c) Potassium
(d) Copper
Answer: (b) Magnesium
Explanation: Magnesium is an alkaline earth metal in Group 2 of the periodic table.

40) Which process is used to obtain common salt from seawater?

(a) Filtration
(b) Crystallization
(c) Evaporation
(d) Sublimation
Answer: (c) Evaporation
Explanation: Seawater is evaporated to leave behind common salt (NaCl).

41) What is the chemical formula for bleaching powder?
- (a) CaCl2
- (b) Ca(OCl)2
- (c) CaCO3
- (d) Ca(OH)2
  Answer: (b) Ca(OCl)2
  Explanation: Bleaching powder is chemically calcium oxychloride Ca(OCl)2.

42) Which gas is produced when an acid reacts with a carbonate?

(a) Hydrogen
(b) Carbon dioxide
(c) Oxygen
(d) Nitrogen
Answer: (b) Carbon dioxide
Explanation: Acids react with carbonates to release carbon dioxide gas, e.g., CaCO3+2HCl→CaCl2+CO2+H2O

43) What is the use of baking soda in cooking?

(a) To neutralize acids
(b) To increase acidity
(c) To release carbon dioxide and make the dough rise
(d) To prevent spoilage
Answer: (c) To release carbon dioxide and make the dough rise
Explanation: Baking soda (NaHCO3) releases CO2 during heating, making the dough soft and spongy.

44) Which acid is used in the preparation of fertilizers?

(a) Hydrochloric acid
(b) Nitric acid
(c) Sulfuric acid
(d) Acetic acid
Answer: (b) Nitric acid
Explanation: Nitric acid (HNO3) is used in making fertilizers like ammonium nitrate.

45) Which compound is responsible for the hardness of water?

(a) Sodium chloride
(b) Calcium bicarbonate
(c) Magnesium sulfate
(d) Both (b) and (c)
Answer: (d) Both (b) and (c)
Explanation: Hardness in water is due to the presence of calcium bicarbonate and magnesium sulfate.

46) Which of the following is a basic salt?

(a) Sodium chloride
(b) Ammonium chloride
(c) Sodium carbonate
(d) Zinc chloride
Answer: (c) Sodium carbonate
Explanation: Sodium carbonate (Na2CO3) is a basic salt formed from a strong base and a weak acid.

47) What is the pH of rainwater that causes acid rain?

(a) Above 7
(b) Below 7
(c) Exactly 7
(d) Neutral
Answer: (b) Below 7
Explanation: Acid rain has a pH below 7 due to the presence of acidic gases like SO2 and NO2

48) Which of the following is used to treat bee stings?

(a) Baking soda
(b) Vinegar
(c) Limewater
(d) Hydrochloric acid
Answer: (a) Baking soda
Explanation: Bee stings are acidic, and baking soda (a base) neutralizes the acid.

49) What happens when a base reacts with an ammonium salt?

(a) Carbon dioxide is released
(b) Ammonia gas is released
(c) Water is formed
(d) A precipitate forms
Answer: (b) Ammonia gas is released
Explanation: Bases react with ammonium salts to release ammonia gas, e.g., NH4Cl+NaOH→NaCl+H2O+NH3

50) What is the primary component of antacids?

(a) Sodium hydroxide
(b) Magnesium hydroxide
(c) Calcium carbonate
(d) Both (b) and (c)
Answer: (d) Both (b) and (c)
Explanation: Antacids commonly contain magnesium hydroxide (Mg(OH)2) and calcium carbonate (CaCO3) to neutralize stomach acid.

51) Which acid is present in curd?

(a) Citric acid
(b) Acetic acid
(c) Lactic acid
(d) Tartaric acid
Answer: (c) Lactic acid
Explanation: Curd contains lactic acid, produced by the fermentation of milk.

52) What is the common name of Na2CO3⋅10H2O?

(a) Baking soda
(b) Washing soda
(c) Bleaching powder
(d) Quicklime
Answer: (b) Washing soda
Explanation: Sodium carbonate decahydrate (Na2CO3⋅10H2O) is commonly known as washing soda.

53) What is the pH range of basic substances?

(a) 0–7
(b) 7–14
(c) 7–10
(d) 1–14
Answer: (b) 7–14
Explanation: Basic substances have a pH greater than 7, ranging from 7 to 14.

54) Which substance is used to remove permanent hardness of water?

(a) Limewater
(b) Baking soda
(c) Washing soda
(d) Slaked lime
Answer: (c) Washing soda
Explanation: Washing soda (Na2CO3) removes permanent hardness by precipitating calcium and magnesium ions.

55) What is the effect of a neutralization reaction?

(a) Increase in pH
(b) Decrease in pH
(c) pH becomes 7
(d) No change in pH
Answer: (c) pH becomes 7
Explanation: In a neutralization reaction, acids and bases react to form salt and water, resulting in a neutral pH.

56) What is the chemical formula of gypsum?

(a) CaSO4⋅2H2O
(b) CaSO4⋅1/2H2O
(c) CaCO3
(d) Ca(OH)2
Answer: (a) CaSO4⋅2H2O
Explanation: Gypsum is calcium sulfate dihydrate.

57) Which gas is released when zinc reacts with sodium hydroxide?

(a) Hydrogen
(b) Oxygen
(c) Carbon dioxide
(d) Ammonia
Answer: (a) Hydrogen
Explanation: Zinc reacts with sodium hydroxide to release hydrogen gas: Zn+2NaOH→Na2ZnO2+H2

58) Which compound is used in whitewashing?

(a) Calcium carbonate
(b) Calcium oxide
(c) Calcium hydroxide
(d) Calcium sulfate
Answer: (c) Calcium hydroxide
Explanation: Calcium hydroxide (Ca(OH)2), also known as slaked lime, is used in whitewashing.

59) Which acid is found in fizzy drinks?

(a) Acetic acid
(b) Carbonic acid
(c) Tartaric acid
(d) Citric acid
Answer: (b) Carbonic acid
Explanation: Fizzy drinks contain carbonic acid, formed by dissolving CO2 in water.

60) What is the effect of adding limewater to an acidic soil?

(a) It increases acidity
(b) It neutralizes acidity
(c) It adds nutrients
(d) It decreases salinity
Answer: (b) It neutralizes acidity
Explanation: Limewater Ca(OH)2 neutralizes acidic soils by raising their pH.

MCQs from the EXERCISE part of the chapter.

1) A solution turns red litmus blue. Its pH is likely to be:
- (a) 1
- (b) 4
- (c) 5
- (d) 10
  Answer: (d) 10
  Explanation: A solution that turns red litmus blue is basic. Basic solutions have a pH greater than 7, and a pH of 10 indicates a moderately strong base.

2) A solution reacts with crushed egg shells to produce a gas that turns lime water milky. The solution contains:

(a) NaCl
(b) HCl
(c) LiCl
(d) KCl
Answer: (b) HCl
Explanation: Crushed egg shells contain calcium carbonate (CaCO3), which reacts with hydrochloric acid (HCl) to release carbon dioxide (CO2), turning limewater milky.

3) 10 mL of a solution of NaOH is completely neutralized by 8 mL of HCl. If we take 20 mL of the same NaOH solution, how much Hcl solution is required to neutralize it?

- (a) 4 mL (b) 8 mL (c) 12 mL (d) 16 mL
  Answer: (d) 16 mL
  Explanation: From the given data:

10 mL of NaOH is neutralized by 8 mL of HCl
Therefore, 1mL of NaOH requires 8/10 =0.8 mL of HCl

For 20 mL of NaOH:

Amount of HCl=20×0.8=16 mL

4) Which one of the following types of medicines is used for treating indigestion?
- (a) Antibiotic
- (b) Analgesic
- (c) Antacid
- (d) Antiseptic
  Answer: (c) Antacid
  Explanation: Indigestion is caused by excess stomach acid, and antacids, such as magnesium hydroxide or sodium bicarbonate, neutralize this acid.

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