Skip to content

Define the following terms : (Class 10 Science 2026, Q25)

questionbuddy.in/q/cbse-10-science-2026-31-5-1-q25-define-terms

ScienceCBSE Class 10 · Board exam 2026, set 31/5/1 · 2 marks · Very short answer

CBSE Class 10 Science 2026: question 25

Set in the CBSE Class 10 board exam of 2026, paper 31/5/1, section B, question 25, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q25 · 2 marks · Very short answerAcids, Bases and Salts

Define the following terms :

  1. (i)

    Olfactory indicator

    1 mark
  2. (ii)

    Water of crystallization

    1 mark

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/5/1.

Hints

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

Hint 1

'Olfactory' refers to the sense of smell.

Hint 2

Think of blue copper sulphate crystals turning white on heating — what is lost?

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) Olfactory indicators are substances whose odour changes in acidic or basic medium, e.g. onion, vanilla essence, clove oil.

    1 mark

  2. (ii) Water of crystallisation is the fixed number of water molecules present in one formula unit of a salt, e.g. 5 in .

    1 mark

Answer: (i) Substances whose smell changes in acid/base; (ii) fixed number of water molecules in one formula unit of a salt.

Where the marks are

  • Correct definition of olfactory indicator (1 mark)
  • Correct definition of water of crystallisation (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 paper2026 board paper, set 31/5/1: 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.