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Solid Calcium oxide reacts… (Class 10 Science 2024, Q1)

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ScienceCBSE Class 10 · Board exam 2024, set 31/2/1 · 1 mark · MCQ

CBSE Class 10 Science 2024: question 1

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

Q1 · 1 mark · MCQChemical Reactions and Equations

Solid Calcium oxide reacts vigorously with water to form Calcium hydroxide accompanied by the liberation of heat. From the information given above it may be concluded that this reaction

  1. (A)is endothermic and pH of the solution formed is more than 7.
  2. (B)is exothermic and pH of the solution formed is 7.
  3. (C)is endothermic and pH of the solution formed is 7.
  4. (D)is exothermic and pH of the solution formed is more than 7.

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

Is heat given out or taken in during the reaction?

Hint 2

Is calcium hydroxide acidic, neutral or basic in water?

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. The reaction is + heat. Heat is given out, so the reaction is exothermic.

    ½ mark

  2. (slaked lime) is a base that dissolves in water as an alkali. So the solution is basic and its pH is more than 7. Option (D) is correct.

    ½ mark

Answer: Exothermic, pH more than 7: option (D)

Where the marks are

  • Chooses option (D): exothermic reaction, pH > 7 (1 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 31/2/1: 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.