The incorrect statements regarding geometrical isomerism are : (A) Propene shows geometrical isomerism. (B) Trans isomer has identical atoms/groups on the opposite sides of the double bond. (C) Cis-but-2-ene has higher dipole moment than trans-but-2-ene. (D) 2-methylbut-2-ene shows two geometrical isomers. (E) Trans-isomer has lower melting point that cis isomer.
Choose the CORRECT answer from the options given below :
(A)(A), (D) and (E) only✓ Correct
(B)(C), (D) and (E) only
(C)(B) and (C) only
(D)(A) and (E) only
Answer: (A)
Solution
Checking each statement:
(A) Propene, CH3−CH=CH2, has two identical hydrogens on the terminal =CH2 carbon, so it cannot show geometrical isomerism — false.
(B) By definition, the trans isomer places identical/similar groups on opposite sides of the double bond — true.
(C) In cis-but-2-ene the two methyl groups lie on the same side, giving a net dipole moment; in trans-but-2-ene the bond dipoles cancel by symmetry, giving zero moment. Cis therefore has the higher dipole moment — true.
(D) 2-methylbut-2-ene, (CH3)2C=CH−CH3, has two identical methyl groups on one double-bond carbon, so it cannot show geometrical isomerism — false.
(E) Trans isomers pack more symmetrically in the solid state and generally have higher, not lower, melting points than the cis isomer — false.
The incorrect statements are (A), (D) and (E).
JEE Main · 2025 · 22 Jan 2025 · Shift 1 · Single correct option
