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Answer the following. (Class 10 Science 2023, Q21a)

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ScienceCBSE Class 10 · Board exam 2023, set 31/1/1 · 2 marks · Very short answer

CBSE Class 10 Science 2023: question 21(a)

Set in the CBSE Class 10 board exam of 2023, paper 31/1/1, section B, question 21(a), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21(a) · 2 marks · Very short answerAcids, Bases and Salts

Answer the following.

  1. (i)

    A compound 'X' which is prepared from gypsum has the property of hardening when mixed with proper quantity of water.
    Identify 'X' and write its chemical formula.

    0 marks
  2. (ii)

    State the difference in chemical composition between baking soda and baking powder.

    0 marks

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

Hints

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

Hint 1

Which substance is used to set fractured bones and is made by heating gypsum?

Hint 2

Baking powder contains baking soda plus one more ingredient that is an acid.

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. (i) Gypsum heated to 373 K loses part of its water and forms Plaster of Paris (calcium sulphate hemihydrate). It sets into a hard mass when mixed with water. So X = Plaster of Paris.

    ½ mark

  2. (i) Formula of X:

    ½ mark

  3. (ii) Baking soda is a single compound, sodium hydrogen carbonate, .

    ½ mark

  4. (ii) Baking powder is a mixture of baking soda () and a mild edible acid such as tartaric acid.

    ½ mark

Answer: (i) X = Plaster of Paris, CaSO₄·½H₂O; (ii) baking soda is NaHCO₃ only, while baking powder is NaHCO₃ + tartaric acid (mild edible acid)

Where the marks are

  • Names Plaster of Paris (½ mark)
  • Writes (½ mark)
  • Baking soda = (½ mark)
  • Baking powder = + tartaric acid (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 paper2023 board paper, set 31/1/1: 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.