IIT JEE Advanced 2007 Paper 2

The possible stereoisomers from trans-2-butene are

H3C |

C

| H

=

H |

C

| CH3

→ H−

CH3 |

C

| Br

−

CH3 |

C

| Br

−H (I) or H3C−

H |

C

| Br

−

H |

C

| Br

−CH3 (II)
Of these, (II) is a meso compound, that is, one half of the molecule is mirror image of the other half, even though it contains a chiral centre. Thus, there is only one stereoisomer.