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Assertion (A): In an… (Class 10 Science SQP 2026-27, Q9)

questionbuddy.in/q/cbse-10-science-2026-27-sqp-q9-ecosystem-energy-available-transfer-trophic

ScienceCBSE Class 10 · Sample paper, session 2026-27 · 1 mark · Assertion-reason

CBSE Class 10 Science sample paper 2026-27: question 9

From the official CBSE sample question paper for 2026-27, 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): In an ecosystem, 1% of energy is available for transfer from one trophic level to the next. Reason (R): An average of 10% of the food eaten by organisms is available for flow in the form of chemical energy.

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

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

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

Hint 1

Recall the '10 percent law' of energy flow.

Hint 2

Compare the percentage in A with that law.

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. By the 10 percent law, about 10% (not 1%) of the energy at one trophic level is passed on to the next. A is false.

  2. On average, about 10% of the food eaten is turned into the organism's body and is available to the next level as chemical energy. R is true.

  3. A is false but R is true, option (D).

    1 mark

Answer: Option (D): A is false but R is true.

Where the marks are

  • Applies the 10% law: A is false and R is true, option (D) (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 paperSample paper 2026-27: 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.