# Why carbonyl compunds are more reactive towards catalytic hydrogenation than alkynes and alkenes?

Alkynes are more reactive towards catalytic hydrogenation than that of alkenes, because they are more unsaturated. [kindly, tell me if these is not the correct reason.].

But why are carbonyl compunds more reactive towards catalytic hydrogenation than alkyenes? The $\ce{C=O}$ in carbonyl group is polar, but how does that affect?

Example:

Option (D): $c>a>b$

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I doubt that it is carbonil group that is hydrogenated. It is more likely, that $C-Cl$ bond will be cleaved here. $COCl$ group is known to be very ready to react. –  permeakra Jan 15 '13 at 7:56