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Salts play a very important… (Class 10 Science 2024, Q37a)

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ScienceCBSE Class 10 · Board exam 2024, set 31/2/1 · 4 marks · Case-based

CBSE Class 10 Science 2024: question 37(a)

Set in the CBSE Class 10 board exam of 2024, paper 31/2/1, section E, question 37(a), for 4 marks. Try it first; the hints and our step-by-step solution are below.

Q37(a) · 4 marks · Case-basedCompetency-basedAcids, Bases and Salts

Salts play a very important role in our daily life. Sodium chloride which is known as common salt is used almost in every kitchen. Baking soda is also a salt used in faster cooking as well as in baking industry. The family of salts is classified on the basis of cations and anions present in them.

  1. (a)

    Identify the acid and base from which Sodium chloride is formed.

    1 mark
  2. (b)

    Find the cation and the anion present in Calcium sulphate.

    1 mark
  3. (c)

    "Sodium chloride and washing soda both belong to the same family of salts." Justify this statement.

    2 marks
  4. (c)

    Define the term pH scale. Name the salt obtained by the reaction of Potassium hydroxide and Sulphuric acid and give the pH value of its aqueous solution.

    2 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/2/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Split NaCl into the part from a base (Na) and the part from an acid (Cl).

Hint 2

A family of salts shares a common ion. Look at the cation in NaCl and in Na₂CO₃.

Hint 3

A salt of a strong acid and a strong base gives a neutral solution.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (a) Sodium chloride forms when an acid neutralises a base: . Acid: hydrochloric acid (HCl).

    ½ mark

  2. (a) Base: sodium hydroxide (NaOH).

    ½ mark

  3. (b) Calcium sulphate is . Cation: .

    ½ mark

  4. (b) Anion: (sulphate ion).

    ½ mark

  5. (c)(a) Salts that have the same cation (or the same anion) are grouped into one family.

    1 mark

  6. (c)(a) Sodium chloride () and washing soda () both contain the same cation, . So both belong to the family of sodium salts, even though their anions ( and ) differ.

    1 mark

  7. (c)(b) [OR] The pH scale is a scale, usually from 0 to 14, for measuring the hydrogen ion () concentration of a solution. A pH below 7 is acidic, 7 is neutral and above 7 is basic.

    1 mark

  8. (c)(b) . The salt formed is potassium sulphate ().

    ½ mark

  9. (c)(b) It comes from a strong acid and a strong base, so its aqueous solution is neutral, with pH = 7.

    ½ mark

Answer: (a) HCl and NaOH; (b) Ca²⁺ and SO₄²⁻; (c)(a) both contain the Na⁺ cation, so both are sodium salts; (c)(b) pH scale measures H⁺ ion concentration (0–14); K₂SO₄; pH = 7

Where the marks are

  • HCl as the acid and NaOH as the base (½ + ½ marks)
  • Ca²⁺ cation and SO₄²⁻ anion (½ + ½ marks)
  • Justifies that both contain the Na⁺ cation, so they are in the same (sodium) family of salts (2 marks)
  • OR: defines the pH scale (1 mark), names potassium sulphate (½ mark), states pH 7 (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Acids, Bases and Salts, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 31/2/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.