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B. I. What is… (Class 10 Science SQP 2026-27, Q39B)

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ScienceCBSE Class 10 · Sample paper, session 2026-27 · 5 marks · Long answer

CBSE Class 10 Science sample paper 2026-27: question 39(B)

From the official CBSE sample question paper for 2026-27, section C, question 39(B), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q39(B) · 5 marks · Long answerThe Human Eye and the Colourful World

B. I. What is dispersion of light? II. Which colour of light deviates the least during dispersion through a prism? III. State why the sky appears dark to an astronaut in outer space. IV. Draw a simple labelled diagram to show how white light splits into different colours while passing through a glass prism.

  1. I

    What is dispersion of light?

    0 marks
  2. II

    Which colour of light deviates the least during dispersion through a prism?

    0 marks
  3. III

    State why the sky appears dark to an astronaut in outer space.

    0 marks
  4. IV

    Draw a simple labelled diagram to show how white light splits into different colours while passing through a glass prism.

    0 marks

Figure in the paper: Simple labelled diagram of a glass prism with a white light ray entering one face and emerging dispersed into a spectrum of colours (violet, indigo, blue, green, yellow, orange, red). See it in the official paper.

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

Different colours have different wavelengths. Which wavelength bends least in glass?

Hint 2

The sky looks blue on Earth because of scattering. What is missing in space?

Hint 3

In the diagram, the most deviated colour lies nearest the base of the prism.

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. Dispersion: The splitting of white light into its component colours (VIBGYOR) when it passes through a transparent medium such as a glass prism. It happens because light of different colours (wavelengths) bends through different angles.

    1 mark

  2. II. Red light deviates the least, because it has the longest wavelength and bends least in glass. Violet deviates the most.

    1 mark

  3. III. Outer space has no atmosphere, so there are no air molecules or fine particles to scatter sunlight. No scattered light reaches the astronaut's eyes from the surroundings, so the sky appears dark.

    1 mark

  4. IV. Diagram: Draw a triangular glass prism. Show a ray of white light striking one face, bending towards the base inside the prism, and emerging from the second face as a band of colours.

    1 mark

  5. Label the spectrum in order: R, O, Y, G, B, I, V, with red at the top (least deviated) and violet at the bottom (most deviated). Also label the glass prism, the white light beam and the spectrum (on a screen).

    1 mark

Answer: I. Splitting of white light into its colours; II. Red; III. No atmosphere, so no scattering of sunlight; IV. Labelled prism diagram with red least and violet most deviated

Where the marks are

  • Correct definition of dispersion (1 mark)
  • Red deviates least (1 mark)
  • No atmosphere, so no scattering, hence dark sky (1 mark)
  • Diagram: prism with white light entering and splitting (1 mark)
  • Diagram: correct VIBGYOR order with labels (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from The Human Eye and the Colourful World, 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.