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Which of the following… (Class 10 Science SQP 2025-26, Q21)

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ScienceCBSE Class 10 · Sample paper, session 2025-26 · 1 mark · MCQ

CBSE Class 10 Science sample paper 2025-26: question 21

From the official CBSE sample question paper for 2025-26, section B, question 21, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q21 · 1 mark · MCQAcids, Bases and Salts

Which of the following substances when dissolved in equal volume of water, will have the highest pH value?

  1. (A)Sulphuric acid
  2. (B)Acetic acid
  3. (C)Magnesium hydroxide
  4. (D)Sodium hydroxide

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2025-26.

Hints

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

Hint 1

First separate the acids from the bases.

Hint 2

Between the two bases, which one dissolves well and gives more hydroxide ions?

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. Acids have pH < 7, so sulphuric acid and acetic acid are ruled out. Bases have pH > 7.

  2. Magnesium hydroxide is only sparingly soluble, so it is a weak base and gives few ions. Sodium hydroxide is a highly soluble strong alkali and gives the most ions.

  3. More ions means a higher pH. So NaOH has the highest pH, option (D).

    1 mark

Answer: Sodium hydroxide, option (D)

Where the marks are

  • Selects sodium hydroxide, the strong soluble base (1 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 paperSample paper 2025-26: 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.