While going through my book, I came across this question and got really confused. Here's what the problem was:
In a pair of diastereomers,
- Both can be laevo-rotatory or both can be dextro-rotatory
- Both can be optically inactive
- One can be optically active other can be optically inactive
- Presence of two chiral carbons is must in both of the isomer
As you can see, this is a multiple correct problem.
I tried going with the definition, Diastereomers are stereoisomers whose molecules are not mirror images of each other
Also, to satisfy this, I believe there should at least be two chiral carbons. So option (4) seems right. But I'm really not able to figure out the others. How can we determine this?