just answer some basics

Q1. A>B>D>C
Q2. what do we have to find out in Q2 ?

@ ASISH ,I HAV DOUBT IN Q1. THT WHY D>C

C is most stable of the four alkenes...

Q2. Last one

for Q1: lower the enthalpy of hydrogenation, stabler the alkene.
Moreover, 'An alkene is stabilised by alkyl substituents on the double bond". This means C is the stablest among'em all. That's why consequently highest heat of hydrogenation.

ur answers r correct asish
my doubt z due to which effect C z more stable thn D