An optically active alkene having molecular formula C$_8$H$_{16$ gives acetone as one of the products on ozonolysis. The structure of the alkene is} 
Ozonolysis shortcuts:
Acetone $\Rightarrow$ (CH$_3$)$_2$C= fragment present
Check symmetry for optical activity
Chiral alkene must lack internal symmetry
Write the correct order of rate of reaction of following with PhN$_2$Cl 
Identify A in the following reaction. 