CBSE Class 12 Mathematics sample paper 2026-27: question 20
From the official CBSE sample question paper for 2026-27, section A, question 20, for 1 mark. Try it first; the hints and our step-by-step solution are below.
Q20 · 1 mark · Assertion-reasonCompetency-basedDifferential Equations
Assertion: The general solution of a differential equation represents a family of curves.
Reason: The derivative of an arbitrary constant is zero.
- (A)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (B)Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (C)Assertion (A) is true but Reason (R) is false.
- (D)Assertion (A) is false but Reason (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
What does an arbitrary constant do to a curve?
Hint 2
How are the constants eliminated when forming the differential equation?
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.
The general solution contains arbitrary constants, so it represents a family of curves.
- 1 mark
Differentiating eliminates these constants because the derivative of a constant is zero. This is why one equation describes the whole family, so the Reason explains the Assertion.
Answer: Option (A)
Where the marks are
- Recognises both statements as true and linked (1 mark)
Revise the chapter
- Chapter: Differential Equations (notes, formulas, where marks are lost and every past question)
More questions from Differential Equations
- Sample paper 2026-27, Q29(A) · 3 marksFind the particular solution of the differential equation x dy+(y-x²e^x)dx=0, given that y(1)=0
- Sample paper 2026-27, Q29(B) · 3 marksFind the particular solution of the differential equation (x²+y²)dy=xy dx, given that y(0)=1
- 2026 board paper, set 65/1/1, Q29(a) · 3 marksFind the general solution of the following differential equation : x²dy/dx = x² + xy + y²
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