Important Questions for Class 10 Science Chapter 2: Acids, Bases and Salts

Acids, Bases and Salts is the second chapter of Class 10 Science. It explains the properties of acids and bases, how they react with metals, metal carbonates and each other, the pH scale, and how salts are formed. It also covers important everyday chemicals such as baking soda, washing soda, bleaching powder and common salt.

Important Questions for Class 10 Science Chapter 2: Acids, Bases and Salts

Acids, Bases and Salts
Medium
Q.
A solution turns red litmus blue, its pH is likely to be

(a) 1
(b) 4
(c) 5
(d) 10
Acids, Bases and Salts
Medium
Q.
A solution reacts with crushed egg-shells to give a gas that turns lime-water milky.
The solution contains

(a) NaCl
(b) HCl
(c) LiCl
(d) KCl
Acids, Bases and Salts
Medium
Q.
10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be

(a) 4 mL
(b) 8 mL
(c) 12 mL
(d) 16 mL
Acids, Bases and Salts
Medium
Q.
Which one of the following types of medicines is used for treating indigestion?

(a) Antibiotic
(b) Analgesic
(c) Antacid
(d) Antiseptic
Acids, Bases and Salts
Medium
Q.
Write word equations and then balanced equations for the reaction taking place when –

(a) dilute sulphuric acid reacts with zinc granules.
(b) dilute hydrochloric acid reacts with magnesium ribbon.
(c) dilute sulphuric acid reacts with aluminium powder.
(d) dilute hydrochloric acid reacts with iron filings.
Acids, Bases and Salts
Medium
Q.
Compounds such as alcohols and glucose also contain hydrogen but are not categorised as acids. Describe an activity to prove it.
Acids, Bases and Salts
Easy
Q.
Why does distilled water not conduct electricity, whereas rain water does?
Acids, Bases and Salts
Medium
Q.
Why do acids not show acidic behaviour in the absence of water?
Acids, Bases and Salts
Medium
Q.
Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9, respectively. Which solution is:

(a) neutral?
(b) strongly alkaline?
(c) strongly acidic?
(d) weakly acidic?
(e) weakly alkaline?
Arrange the pH in increasing order of hydrogen-ion concentration.
Acids, Bases and Salts
Easy
Q.
Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH3COOH) is added to test tube B. Amount and concentration taken for both the acids are same. In which test tube will the fizzing occur more vigorously and why?
Acids, Bases and Salts
Easy
Q.
Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.
Acids, Bases and Salts
Medium
Q.
A milkman adds a very small amount of baking soda to fresh milk.

(a)Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b)Why does this milk take a long time to set as curd?
Acids, Bases and Salts
Medium
Q.
Plaster of Paris should be stored in a moisture-proof container. Explain why?
Acids, Bases and Salts
Medium
Q.
What is a neutralisation reaction? Give two examples.
Acids, Bases and Salts
Medium
Q.
Give two important uses of washing soda and baking soda.

Important Questions for Class 10 Science Chapter 2: Acids, Bases and Salts

These CBSE important questions cover the reaction of acids with metal carbonates, the test for carbon dioxide, the uses of common salts and the parts of a salt. Every question has a clear answer with the chemical equations students need for the board exam.

Q1. Metal carbonates and hydrogen carbonates react with acids to give (1 mark)

  1. carbon dioxide
  2. hydrogen
  3. sulphur dioxide
  4. carbon monoxide

Answer:

(a) carbon dioxide.

Metal carbonate / hydrogen carbonate + acid → salt + water + carbon dioxide. For example,

Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂.

Q2. Name the gas evolved when dilute sulphuric acid reacts with sodium carbonate. Write the chemical equation for the reaction involved. (2 marks)

Answer:

Carbon dioxide gas is evolved when dilute sulphuric acid reacts with sodium carbonate.

Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂↑

When this gas is passed through lime water, the lime water turns milky, which confirms that the gas is carbon dioxide.

Carbon dioxide gas test using lime water
Carbon dioxide from sodium carbonate and sulphuric acid turns lime water milky

Q3. (i) Give uses of the following substances: (a) Baking soda (b) Washing soda (c) Common salt. (ii) What is bleaching powder? Write its uses. (5 marks)

Answer:

(i) (a) Baking soda (NaHCO₃)

  • It is used to make baking powder (a mixture of baking soda and tartaric acid), which makes cakes and bread soft and spongy.
  • It is an ingredient in antacids.

(b) Washing soda (Na₂CO₃·10H₂O)

  • It is used for softening hard water.
  • It is used as a cleaning agent for domestic purposes.

(c) Common salt (NaCl)

  • It is used in our daily food.
  • It is used as a preservative.

(ii) Bleaching powder is calcium oxychloride (CaOCl₂). Its uses are:

  • It is used for disinfecting drinking water to make it free from germs.
  • It is used for bleaching cotton and linen in the textile industry.

Q4. Name the parts of a salt. (2 marks)

Answer:

A salt has two parts: one part comes from an acid and the other part comes from a base. The positive ion (cation) comes from the base and the negative ion (anion) comes from the acid. For example, in sodium chloride (NaCl), Na⁺ comes from sodium hydroxide (base) and Cl⁻ comes from hydrochloric acid (acid).

Related Study Material on Extramarks

Q.1 In the question, a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below the question. 
Assertion (A): Baking powder is used in making cakes.
Reason (R): The carbon dioxide gas released when baking powder is mixed with water (which is present in the dough) causes the cake to rise and makes it spongy.

(a) Both the assertion and the reason are true, and the reason is the correct explanation of the assertion.

(b) Both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.

(c) The assertion is true, but the reason is false.

(d) The assertion is false, but the reason is true.

Marks:1
Ans

(a) Both the assertion and the reason are true, and the reason is the correct explanation of the assertion.


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FAQs (Frequently Asked Questions)

One-mark questions cover definitions, pH values, formula identification, and short factual answers. Three-mark questions ask for reactions, concept differences, or short explanations. Five-mark questions ask for preparation, properties, and uses of common salt products, or the chlor-alkali process with all products and their uses.

A strong acid produces more H+ ions per molecule and ionises completely in water. HCl and HNO3 are strong acids. A concentrated acid simply means a large amount of the acid is dissolved in a small volume of water. Concentration refers to quantity. A dilute strong acid and a concentrated weak acid are completely different things.

The most common mistakes are: assuming lower pH always means more concentrated acid (it means more H+ ions, which is about strength); thinking a neutral solution has no ions (it has equal H+ and OH- ions); and confusing the direction of the scale — acids are below 7, bases are above 7.

Very important. Both appear in 3-mark and 5-mark questions every year in CBSE 2026 papers. The examiner tests formula, preparation reaction, uses, and why Plaster of Paris must be stored in moisture-proof containers. These combine memory and application.

Case-based questions usually present a scenario: a milkman adding baking soda to milk, a farmer treating acidic soil, a student spilling acid. Two to three questions follow, requiring students to apply concepts of pH, neutralisation, and acid-base behaviour rather than just recalling facts.

The most tested reactions are acid + metal, acid + carbonate, acid + metal oxide, neutralisation, the chlor-alkali process, manufacture of bleaching powder, baking soda on heating, and Plaster of Paris to gypsum conversion. Students must know both the word equation and the balanced chemical equation for each