Question

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Cis form of alkene is found to be more polar than the trans form
Reason (R): Dipole moment of trans isomer of 2-butene is zero. In the light of the above statements.
Choose the correct answer from the options given below :

• A. Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
• B. (A) is true but (R) is false
• C. Both (A) and (R) are true and (R) is the correct explanation of (A)
• D. (A) is false but (R) is true

Answer 1

Answer: (C)

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

Answer 2

The dipole moment is a vector quantity. In the trans isomer of 2-butene, the dipoles of substituents are equal in magnitude but opposite in direction, resulting in a net dipole moment of zero ($\mu = 0$). However, in the cis isomer, the dipoles do not cancel out, making the molecule polar with $\mu > 0$. Thus, the dipole moment of the cis form is greater than the trans form.

Cis isomer: $\mu > 0$, Trans isomer: $\mu = 0$.

Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.