Questions

Assertion (A) & Reason (B) MCQ

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2 questions · auto-graded multiple-choice test.

MCQ 11 Mark
Assertion (A): A relation $R =\{( a , b )$ : $| a - b |<3\}$ defined on the set $A =\{1,2,3,4\}$ is reflexive.
Reason (R): A relation $R$ on the set $A$ is said to be reflexive if for $(a, b) \in R$ and $(b, c) \in R$, we have $(a, c) \in R$.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • A is true but R is false.
  • D
    A is false but R is true.
Answer
Correct option: C.
A is true but R is false.
(c) A is true but R is false.
Explanation: Assertion is true because for each element $a \in A ,| a - a |=0<3$, so $(1,1) \in R,(2,2) \in R,(3,3) \in R,(4,4)$ $\in R$ therefore R is reflexive.
Reason is false because a relation $R$ on the set $A$ is said to be transitive if for $(a, b) \in R$ and $(b, c) \in R$, we have $(a, c) \in R$
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MCQ 21 Mark
Assertion (A): The rate of change of area of a circle with respect to its radius $r$ when $r=6 cm$ is $12 \pi cm^2 / cm$.
Reason (R): Rate of change of area of a circle with respect to its radius r is $\frac{d A}{d r}$, where A is the area of the circle.
  • Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true
Answer
Correct option: A.
Both A and R are true and R is the correct explanation of A.
(a) Both A and R are true and R is the correct explanation of A .
Explanation: Both A and R are true and R is the correct explanation of A .
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