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An element 'M' with… (Class 10 Science SQP 2023-24, Q28a)

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ScienceCBSE Class 10 · Sample paper, session 2023-24 · 3 marks · Short answer

CBSE Class 10 Science sample paper 2023-24: question 28(a)

From the official CBSE sample question paper for 2023-24, section C, question 28(a), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q28(a) · 3 marks · Short answerMetals and Non-metals

An element 'M' with electronic configuration 2 8 3 combines separately with , anions. Write the chemical formulae of the compounds formed. Predict with the suitable reason the nature of the bond formed by element 'M' in general. How will the electrical conductivity of the compounds formed vary with respect to 'M'?

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

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

Hint 1

Count the valence electrons of M to find its valency.

Hint 2

Metals that lose electrons form ions. Think about when ions are free to move and carry current.

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. M (2, 8, 3) has 3 valence electrons, so its valency is 3 and it forms . Formulae of the compounds: with it forms ; with it forms .

    1 mark

  2. Nature of bond: ionic. M is a metal that easily loses its 3 valence electrons to form the cation. It then attains the stable configuration of neon (2, 8), and the cation is held to the anions by electrostatic attraction.

    1 mark

  3. Conductivity: M, a metal, conducts electricity in the solid state. Its ionic compounds do not conduct in the solid state, because the ions are fixed in the crystal. They do conduct in the molten state or in aqueous solution, where the ions are free to move.

    1 mark

Answer: and ; ionic bond (M loses 3 electrons to attain the neon configuration); the compounds conduct only when molten/dissolved, unlike M, which conducts in the solid state.

Where the marks are

  • Correct formulae and (1 mark)
  • Ionic bond, with the reason that M loses 3 electrons to get the stable (2, 8) configuration (1 mark)
  • Compounds conduct in molten/aqueous state but not in solid state, unlike metal M (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Metals and Non-metals, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2023-24: 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.