Stereoisomer question?

Question

Which statements about stereoisomers are true?

I Enantiomers and diastereomers have the same physical properties.
II 50/50 mixtures of R and S enantiomers are called racemic mixtures.
III Meso isomers rotate the plane of plane polarised light.
IV Dextrorotatory compounds rotate plane polarised light to the right.

Select one:
a. I, II
b. II, III
c. II, IV
d. III, IV

Answer 1

c. II, IV



You just need to learn that a 50/50 mixture of R and S is a racemic mixture. It is formed when a Sn1 reaction occurs on a chiral atom. Dextrorotatory rotates to the right, laevorotatory rotates to the left.



In terms of I, enantiomers DO have the same physical properties but diastereoisomers DO NOT. In terms of IV, a MESO isomer is one that has a plane of symmetry between the chiral atoms causing it to be optically inactive.

Answer 2

2 and 4. Racemic mixtures are mixtures that contain equal parts of both enantiomers and therefore don't rotate plane-polarized light. Dextrorotatory mixtures rotate light clockwise (I assume that's what you meant by right)

Answer 3

c. II, IV. That is the correct answer about Stereoisomers.