Question

Which of the following pairs of isomers will rotate the plane polarised light in exactly equal amounts (same magnitude) but in opposite directions?

• A. Diastereomer
• B. Enantiomer
• C. Cis-trans isomer
• D. None of these

Answer 1

The correct option is B Enantiomer

Enantiomers are non-superimposable mirror images and they are optically active.
Enantiomers will rotate the plane of polarisation in exactly equal amounts (same magnitude) but in opposite directions.
Dextrorotary designated as (+) gives clockwise rotation (to the right) while leavorotatory designated as (-), gives anti-clockwise rotation (to the left).
Hence option b is correct.