in organic chemistry why there are so many exceptions present?

@ shivam 
the reason is that they have lot of compounds and they all have nearly diffrent structure . 
thatswhy they posses exception , and all of the compounds are nearly same but 1 of them will show diffrent properties due to some extra group present in them . 
thats the main thing . structure , melting and boiling point and the no of groups attached to that perticular compound and their hybridisation . 
these all thing govern nearly all prperties that comes under exception . 
”HOPE IT CLEARS YOUR DOUBT 
ALL THE BEST ..