Assertion (A) & Reason (B) MCQ

MCQ 11 Mark

Assertion (A): When two lines intersect such that they form an angle of $35^{\circ}$ then its adjacent angle measures $55^{\circ}$ and vertically opposite angle measures $35^{\circ}$.
Reason (R): Vertically opposite angles are always equal.

A
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
B
Both Assertton (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
C
Assertion (A) is true but Reason (R) is false.
✓
Assertion (A) is false but Reason (R) Is true.

Answer

Correct option: D.

Assertion (A) is false but Reason (R) Is true.

(d): When two lines intersect, any two adjacent angles form a linear pair. So, if one of the angles measures $35^{\circ}$ then the adjacent angle measures $180^{\circ}-35^{\circ}=145^{\circ}$.
$\therefore A$ is false.
R is true since vertically opposite angles are always equal.

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MCQ 21 Mark

Assertion (A): Two right angles are always complementary angles.
Reason (R): An angle which is equal to twice its complement measures $60^{\circ}$.

A
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
B
Both Assertton (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
C
Assertion (A) is true but Reason (R) is false.
✓
Assertion (A) is false but Reason (R) Is true.

Answer

Correct option: D.

Assertion (A) is false but Reason (R) Is true.

(d): A is false since two right angles are supplementary, i.e., $90^{\circ}+90^{\circ}=180^{\circ}$.
R is true since the complement of an angle of $60^{\circ}$ is $30^{\circ}$ and $60^{\circ}=2 \times 30^{\circ}$.

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MCQ 31 Mark

Assertion (A): Two adjacent angles have a common arm and a common vertex.
Reason (R): Vertically opposite angles have a common vertex.

A
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
✓
Both Assertton (A) and Reason (R) are true and 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.

Answer

Correct option: B.

Both Assertton (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).

(b): A is true since two adjacent angles have a common arm and a common vertex.
R is true since the point of intersection of the two lines is the common vertex of the two vertically opposite angles.
But R is not the correct explanation of A .

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MCQ 41 Mark

Assertion (A): When two straight lines intersect, two pairs of vertically opposite angles are formed.
Reason (R): Vertically opnosite anoles are alwavs sumplementary.

A
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
B
Both Assertton (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
✓
Assertion (A) is true but Reason (R) is false.
D
Assertion (A) is false but Reason (R) Is true.

Answer

Correct option: C.

Assertion (A) is true but Reason (R) is false.

(c): A is true because two pairs of vertically opposite angles are formed when two straight lines intersect.
$R$ is false since vertically opposite angles are equal (not supplementary).

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MCQ 51 Mark

Assertion (A): Two angles which form a linear pair are always supplementary.
Reason (R): Any two angles, sum of whose measures is $180^{\circ}$, are said to be supplementary.

✓
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
B
Both Assertton (A) and Reason (R) are true and 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.

Answer

Correct option: A.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

(a): Two angles form a linear pair if they are adjacent angles and their sum is equal to $180^{\circ}$.
So, any two angles which form a linear pair are always supplementary.
$\therefore A$ is true.
R is also true (by the definition of supplementary angles) and R is the correct explanation of A .

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MATHS Assertion (A) & Reason (B) MCQ

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