Question

Assertion : If angles ' $a$' and ' $b$ ' form a linear pair of angles and $a=40°$, then $b={150}^{\circ }.$
Reason : Sum of linear pair of angles is always $180°$
Which of the following is correct.

• A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
• B. If both Assertion and Reason are correct, Reason is not the correct explanation of Assertion.
• C. If Assertion is correct but Reason is incorrect.
• D. If Assertion is incorrect but Reason is correct.

Answer 1

The correct option is D

If Assertion is incorrect but Reason is correct.

Explanation for the correct option:

Determining the correct statement using the properties of angles:

Assertion: If angles '$a$' and ' $b$ ' form a linear pair of angles and $a=40°$, then $b={150}^{\circ }$
if two angles form a linear pair the sum is always $180°$
$a+b={180}^{\circ }$

Here, $a+b=40°+150°={190}^{\circ }$

Which is not equal to $180°$
Hence Assertion is False

Reason: The sum of linear pair of angles is always $180°$ because they form a straight angle.

Sum of angles a and b is not $180°$.

They are not linear pair.
Assertion is incorrect but the reason is correct.

Hence, option (D) is the correct answer.