Which of the following compounds is an optically active compound?

When does a given organic compound exhibit optical activity?

The necessary and sufficient condition for the existence of enantiomers is ...........

The structural formula of cocaine is shown below. How many stereogenic carbon atoms are there in this molecule?

The concentration of an organic compound in chloroform is $6.15 \ g$ per $100 \ mL$ of solution. $A$ portion of this solution in a $5 \ cm$ polarimeter tube causes an observed rotation of $-1.2^{\circ}$. What is the specific rotation of the compound?

Which of the following compounds is not chiral?