Chemistry - STEREO ISOMERISM Question with Solution | TestHub
Match the Column :
Column I | Column II |
|---|---|
(A) | (P) Centre of symmetry |
(B) | (Q) C2-axis of symmetry |
(C) | (R) Plane of symmetry |
(D) | (S) Optically active |
| (T) C3-axis of symmetry |
Options:
Answer:
Solution:
Ans. (A) P, Q, R, T ; (B) R ; (C) P ; (D) Q, S.
Sol. (A) The cage has a C3-axis through the centre of the hexagon, three C2-axes perpendicular to it, a centre of symmetry and several planes of symmetry (D3d), so it matches P, Q, R and T.
(B) cis-1,2-Dichlorocyclohexane has only a plane of symmetry bisecting the C1-C2 bond and the opposite bond (Cs); no axis, no centre, and it is not optically active. Matches R only.
(C) The 1,4-pattern (Cl up at C1, Cl down at C4 ; Br up at C2, Br down at C5) gives a centre of symmetry only (S2 = Ci). Matches P only.
(D) The Fischer projection is (2S,3S)-2,3-dichlorobutane : the two centres have the same configuration, so the molecule is chiral (optically active) and possesses a C2-axis through the midpoint of the C2-C3 bond. Matches Q and S.
