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When magnesium ribbon is… (Class 10 Science 2024, Q21)

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ScienceCBSE Class 10 · Board exam 2024, set 31/3/1 · 2 marks · Very short answer

CBSE Class 10 Science 2024: question 21

Set in the CBSE Class 10 board exam of 2024, paper 31/3/1, section B, question 21, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21 · 2 marks · Very short answerChemical Reactions and Equations

When magnesium ribbon is burnt in air, an ash of white colour is produced. Write chemical equation for the reaction giving the chemical name of the ash produced. State the type of chemical reaction giving justification for your answer.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/3/1.

Hints

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

Hint 1

Magnesium reacts with the oxygen of air.

Hint 2

Count the products. How many substances are formed?

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. Balanced chemical equation:

    ½ mark

  2. The white ash is magnesium oxide, .

    ½ mark

  3. Type of reaction: combination reaction.

    ½ mark

  4. Justification: two reactants, magnesium and oxygen, combine to form a single product, magnesium oxide.

    ½ mark

Answer: ; ash = magnesium oxide; combination reaction (two substances form a single product)

Where the marks are

  • Balanced equation (½ mark)
  • Names the ash as magnesium oxide (½ mark)
  • States combination reaction (½ mark)
  • Justifies: two substances combine to form one product (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Chemical Reactions and Equations, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 31/3/1: 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.