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Aavya and Vihan are… (Class 10 Science SQP 2026-27, Q28)

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ScienceCBSE Class 10 · Sample paper, session 2026-27 · 4 marks · Long answer

CBSE Class 10 Science sample paper 2026-27: question 28

From the official CBSE sample question paper for 2026-27, section B, question 28, for 4 marks. Try it first; the hints and our step-by-step solution are below.

Q28 · 4 marks · Long answerCompetency-basedMetals and Non-metals

Aavya and Vihan are studying the properties of metals in school. They decide to design and conduct an experiment to test the relative conduction of heat by metals. They use the apparatus (Figure) with rods of five different metals aluminium, silver, copper, iron and zinc attached to a central point. This central point is heated using a burner. The metal rods are of equal length and thickness. They observe that the candles at the end of the rods fall at different times. (Study the graph)

  1. A

    On the basis of the graph obtained, which metal is the best conductor of heat?

    0 marks
  2. B

    Gold is a better conductor of heat than aluminium but it is not as good as copper. The time taken for the candle to drop if one of the rods were made of gold would have been: (i) 15 s (ii) 20 s (iii) 35 s (iv) 10 s

    1. (i)15 s
    2. (ii)20 s
    3. (iii)35 s
    4. (iv)10 s
    0 marks
  3. C

    Attempt either sub-part C or D. The length of all the metal rods is increased by 20% without any change in the thickness. Will the time required for the candles to drop be affected? How and why?

    0 marks

  4. OR

    D

    Mayank tries the experiment with an apparatus similar to figure (1). He ensures the length of all metal rods is the same. However, the thickness of rods is not the same in his apparatus. Will the inference he draws on the basis of his experiment be correct? Justify your answer.

    0 marks

Figure in the paper: Apparatus: five metal rods of equal length and thickness radiating from a central point heated by a burner, each rod with a candle attached at its tip. Bar graph titled 'Time take for the candle to drop', y-axis Time/s (0 to 70), x-axis Metals: Silver about 10 s, Copper about 15 s, Aluminium about 30 s, Zinc about 50 s, Iron about 60 s. 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

A better conductor gets heat to the candle sooner, so look for the shortest bar.

Hint 2

Place gold on the graph between the two metals it is compared with.

Hint 3

For C and D, think about the fair-test idea: what changes when length or thickness changes?

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. The candle on the silver rod drops first (about 10 s). Heat reached its end fastest, so silver is the best conductor of heat.

    1 mark

  2. B. Gold conducts better than aluminium (30 s) but worse than copper (15 s). Its time must lie between 15 s and 30 s, so the answer is (ii) 20 s.

    1 mark

  3. C. Yes. The time taken for every candle to drop will increase, but the order in which the candles fall stays the same (silver, copper, aluminium, zinc, iron).

    1 mark

  4. C (reason). In conduction, heat passes from particle to particle by vibration. In a longer rod, heat must travel a greater distance to reach the candle, so it takes more time.

    1 mark

  5. D. No, Mayank's inference will not be correct. For a fair test, only the material of the rod should change; length and thickness must be the same for all rods.

    1 mark

  6. D (reason). The time also depends on thickness, because a thicker rod takes more time for its far end to heat up. The candle times would then reflect both the metal and the thickness, so the metals cannot be compared correctly.

    1 mark

Answer: A. Silver; B. (ii) 20 s; C. Yes, every candle takes longer (order unchanged) because heat travels a longer distance; D. No, thickness also affects the time, so the comparison is not fair.

Where the marks are

  • Identifies silver as the best conductor (1 mark)
  • Chooses 20 s, between copper and aluminium (1 mark)
  • C: time increases for all metals and the order stays the same (1 mark)
  • C: heat has to be conducted over a longer distance (1 mark)
  • D: inference not correct, as rod dimensions must be the same (1 mark)
  • D: a thicker rod takes more time to conduct heat, so the test is not fair (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Metals and Non-metals, 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.