Question

(a.) Both the Assertion 'A' and the Reason 'R' are correct and the Reason 'R' is the
correct explanation of the Assertion 'A'.
(b.) The Assertion ‘A’ and Reason 'R' are correct but the Reason 'R' is not correct
explanation for the Assertion 'A'.
(c.) Assertion 'A' is true but the Reason 'R' is false.
(d.) The statement of the Assertion 'A' is false but the Reason 'R' is true.
(18.) assertion A: The stars twinkle while the planets do not.
Reason R: The stars are much bigger in size than the planets.
(19.) Assertion A: When a bicycle is in motion, the force of friction is exerted by the ground
on the two wheels is always in the forward direction.
Reason R: The frictional force acts only when the bodies are in contact.
(20.) Assertion A: Polyester is synthesized from petrochemicals by linking ester units.
Reason R: Polyester is a natural fibre.​

Answer 1

Answer:

I don't understand

Explanation:

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