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Assertion (A): Melting point… (Class 10 Science 2023, Q20)

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ScienceCBSE Class 10 · Board exam 2023, set 31/6/1 · 1 mark · Assertion-reason

CBSE Class 10 Science 2023: question 20

Set in the CBSE Class 10 board exam of 2023, paper 31/6/1, section A, question 20, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q20 · 1 mark · Assertion-reasonCompetency-basedCarbon and its Compounds

Assertion (A): Melting point and boiling point of ethanol are lower than that of sodium chloride.

Reason (R): The forces of attraction between the molecules of ionic compounds are very strong.

  1. (A)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of (A).
  2. (B)Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of (A).
  3. (C)Assertion (A) is true, but Reason (R) is false.
  4. (D)Assertion (A) is false, but Reason (R) is true.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/6/1.

Hints

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

Hint 1

Compare the bonding in ethanol and in NaCl.

Hint 2

Stronger attractive forces need more energy to overcome.

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. Ethanol is a covalent compound with weak intermolecular forces, so it has low melting and boiling points.

  2. NaCl has strong electrostatic forces of attraction between its ions, giving it high melting and boiling points. Both statements are true and R explains A. Hence the answer is option (A).

    1 mark

Answer: Option (A)

Where the marks are

  • Both true, R explains A (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Carbon and its Compounds, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 31/6/1: 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.