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What is a rainbow ? "We see… (Class 10 Science 2025, Q25b)

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ScienceCBSE Class 10 · Board exam 2025, set 31/6/1 · 2 marks · Very short answer

CBSE Class 10 Science 2025: question 25(b)

Set in the CBSE Class 10 board exam of 2025, paper 31/6/1, section B, question 25(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q25(b) · 2 marks · Very short answerThe Human Eye and the Colourful World

What is a rainbow ? "We see a rainbow in the sky only after the rainfall." Why ?

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/6/1.

Hints

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

Hint 1

What does a glass prism do to white light?

Hint 2

After rain, what is present in the air that can behave like many small prisms?

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. A rainbow is a natural spectrum of seven colours that appears in the sky after a rain shower, on the side opposite to the Sun.

    1 mark

  2. After rainfall, tiny water droplets remain suspended in the air. Each droplet acts like a small prism: it refracts and disperses the incoming sunlight, reflects it internally, and refracts it again as it comes out. The colours then reach the eye separately. Without these droplets no rainbow can form, so it is seen only after rain.

    1 mark

Answer: A rainbow is a natural spectrum in the sky; it forms only after rain because suspended water droplets act as tiny prisms that refract and disperse sunlight.

Where the marks are

  • Defines a rainbow as a natural spectrum seen after a rain shower (1 mark)
  • Water droplets act as tiny prisms that refract, disperse and internally reflect sunlight (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 paper2025 board paper, set 31/6/1: 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.