How many optically active stereoisomers are possible for tri-sec-buty1methane?

Options

A. Eight
B. Four
C. Six
D. Two

Answer

B

Explanation

Each sec-buty`1` group has a chiral carbon that can be `R` or `S`. Since all three alky`1` groups are equivalent, the order of groups is immaterial: `RSR` in the same as `SR R` or `R RS`. The four isomers are: `R R R` and `SSS`: and `R RS` and `SSR`. They form two piars of enantiomers.