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Four identical resistors of… (Class 10 Science 2025, Q15)

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ScienceCBSE Class 10 · Board exam 2025, set 31/2/1 · 1 mark · MCQ

CBSE Class 10 Science 2025: question 15

Set in the CBSE Class 10 board exam of 2025, paper 31/2/1, section A, question 15, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q15 · 1 mark · MCQElectricity

Four identical resistors of each are connected in series to form a square ABCD as shown in the figure. The resistance of the network between the two points 1 and 2 is :

  1. (A)
  2. (B)
  3. (C)
  4. (D)

Figure in the paper: A square loop of four resistors with corners A (top-left), B (top-right), D (bottom-right) and C (bottom-left). Terminal 1 is connected to corner A from above and terminal 2 is connected to corner B from above. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/2/1.

Hints

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

Hint 1

Trace the two different routes from A to B.

Hint 2

Combine the two routes using the parallel formula.

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. Points 1 and 2 are joined to the adjacent corners A and B. Between A and B there are two paths:

    • the single resistor AB:
    • the path A–C–D–B:

  2. These two paths are in parallel:

  3. Answer: **(C) **.

    1 mark

Answer: , option (C)

Where the marks are

  • Finds the and paths in parallel and gets , option (C) (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Electricity, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 31/2/1: 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.