Class 7 Science Chapter 4 Practice Question Answers - Acids, Base and Salts

Q1. When CO₂ gas is passed through limewater, it turns milky. Which of the following compounds is

responsible for this milkiness ?
(a) Calcium oxide
(b) Calcium chloride
(c) sodium carbonate
(d) Calcium carbonate
Ans: (d)
Calcium carbonate is responsible for this milkiness.

Q2. Which of the following ion is responsible for the acidic nature of hydrochloric acid ?
(a) Hydrogen ion
(b) Hydroxide ion
(c) Chloride ion
(d) Hydrochloride ion
Ans: (a)
Hydrogen ion is responsible for the acidic nature of hydrochloric acid.

Q3. Distilled water is:
(a) acidic
(b) basic
(c) neutral
(d) none of these
Ans: (c)
Distilled water is neutral.

Q4. Ammonia that turns red litmus blue is:
(a) acidic
(b) basic
(c) neutral
(d) none of these
Ans: (b)
Ammonia is basic.

Q5. An antacid tablet is given to a person when he suffers from:
(a) obesity
(b) acidity
(c) dog bite
(d) none of these
Ans: (b)
An antacid is a tablet of curing acidity.

Q6. Ant’s bite injects:
(a) acetic acid
(b) formic acid
(c) hydrochloric acid
(d) none of these
Ans: (b)
Ant’s bites injects formic acid.

Q7. The acid that our stomach releases is:
(a) sulphuric acid
(b) nitric acid
(c) hydrochloric acid
(d) formic acid
Ans: (c)
Our stomach releases hydrochloric acid (HCl).

Q8. Neutralisation reaction is the reaction between:
(a) acid and base
(b) salt and water
(c) base and salt
(d) acid and salt
Ans: (a)
Neturalisation reaction is between acid and base.

Q9. When the soil is too acidic, it is treated with:
(a) salt
(b) water
(c) base
(d) acid
Ans: (c)
If the soil is acidic, it is treated with base.

Q10. Quick lime is used in soil when the soil is:
(a) basic
(b) acidic
(c) salty
(d) neutral
Ans: (b)
If the soil is acidic quick lime is used in soil.

Q11. If the soil is too basic, it is treated with:
(a) quicklime
(b) salt
(c) organic matter
(d) water
Ans: (c)
The soil is basic so it is treated with organic matter.

Q12. The factory waste are neutralised by adding:
(a) acidic substances
(b) salts
(c) basic substances
(d) water
Ans: (c)
The factory waste are neutralised by basic substances.

Q13. Soap is:
(a) acidic
(b) basic
(c) neutral
(d) salt
Ans: (b)
Soap is basic.

Q14. Litmus is a natural indicator which is extracted from:
(a) vinegar
(b) citrus fruits
(c) lichens
(d) spinach
Ans: (c)
Litmus is extracted from lichens.

Q15. The colour of litmus in distilled water is:
(a) red
(b) green
(c) blue
(d) purple
Ans: (d)
The colour of litmus in distilled water is purple.

Q16. Tartaric acid is found in:
(a) vinegar
(b) curd
(c) amla
(d) tamarind
Ans: (d)
Tartaric acid is found in tamarind.

Q17. Calcium hydroxide is found in:
(a) soap
(b) lime water
(c) vinegar
(d) milk of magnesia
Ans: (b)
Calcium hydroxide is found in lime water.

Q18. Citric acid is found in:
(a) fruits
(b) vegetables
(c) citrus fruits
(d) all of these
Ans: (c)
Citric acid is found in citrus fruits.

Q19. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of solution ?
(a) Acid and base
(b) Base and neutral
(c) Acid apd neutral
(d) None of these
Ans: (b)
The nature of solution is base and neutral.

Q20. What will the effect on turmeric with common salt ?
(a) Turns red
(b) No effect
(c) Turns blue
(d) Turns green
Ans: (a)
The effect on turmeric with common salt turns red.

Q21. Ascorlic acid is found in:
(a) citrus fruits
(b) fruits
(c) curd
(d) spinach
Ans: (a)
Ascorbic acid is found in citrus fruits.

Q22. Magnesium hydroxide is found in:
(a) soap
(b) lime water
(c) milk of magnesia
(d) vegetable
Ans: (c)
Magnesium hydroxide is found in milk of magnesia.

Q23. Which of the following turns red litmus blue ?
(a) Bases
(b) Acids
(c) Salts
(d) None of these
Ans: (a)
Base turns red litmus blue.

Q24. Which of the following turns blue litmus red ?
(a) Bases
(b) Acids
(c) Salts
(d) None of these
Ans: (b)
Acids turn blue litmus red.

Q25. Which of the following substances makes the fruits sound.
(a) Acids
(b) Salts
(c) Bases
(d) None of these
Ans: (a)
Acids make the fruit sour.

Q26. The products of neutralisation reactions are:
(a) salt and water
(b) acid and base
(c) base and salt
(d) acid and water
Ans: (a)
In neutralisation reaction acid and base react to give salt and water.

Q27. Which of the following is not an indicator ?
(a) Litmus
(b) Phenolphthalein
(c) Turmeric
(d) None of these
Ans: (d)
All these are indicators.

Q28. Which of the following turns pink solution of a phenolphthalein into a colourless solution ?
(a) Bases
(b) Acids
(c) Salt
(d) None of these
Ans: (b)
Acids turn pink solution of phenolphthalein into a colourless solution.

Q29. Which of the following turns colourless solution of phenol¬phthalein into pink solution ?
(a) Salt
(b) Base
(c) Acid
(d) All of these
Ans: (b)
Base turns colourless solution of phenolphthalein into pink solution.

Q30. Acids and bases react to produce:
(a) salt and acid
(b) salt and water
(c) salt and hydrogen gas
(d) none of these
Ans: (b)
Acid and bases react to produce salt and water.