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Assertion (A): Highest… (Class 10 Science 2026, Q9)

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ScienceCBSE Class 10 · Board exam 2026, set 31/4/1 · 1 mark · Assertion-reason

CBSE Class 10 Science 2026: question 9

Set in the CBSE Class 10 board exam of 2026, paper 31/4/1, section A, question 9, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q9 · 1 mark · Assertion-reasonCompetency-basedOur Environment

Assertion (A): Highest percentage of pesticides is found in tertiary consumers in a food chain.

Reason (R): Chemicals / pesticides get accumulated progressively at each trophic level.

  1. (A)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
  2. (B)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
  3. (C)Assertion (A) is true, but Reason (R) is false.
  4. (D)Assertion (A) is false, but Reason (R) is true.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/4/1.

Hints

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

Hint 1

Recall biological magnification.

Hint 2

Does accumulation at each level explain why the top level has the most?

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. Through biological magnification, pesticides accumulate progressively at each trophic level. The highest trophic level (tertiary consumers) therefore has the maximum concentration.

  2. R explains A, so both are true and R is the correct explanation. Answer: option (A).

    1 mark

Answer: (A)

Where the marks are

  • Both true and R explains A via biomagnification, option (A) (1 mark)

Revise the chapter

  • Chapter: Our Environment (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Our Environment, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 31/4/1: 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.