Which of the following compounds exhibits stereoisomerism ?

How many optically active stereoisomers are possible for butane -2, 3-diol ?

Correct order of nucleophilicity

The possible number of alkynes with the formula C5H8 is

How many different alcohols (excluding optical isomers) are possible with the molecular formula C4H1

Optical isomers possible for the given compound is : CH3 – CH(OH) – CH(OH) – CH3