Why does the C=O group react differently from the C=C group? Show an example of the difference.

When carbonyl reacts with the nucleophile, form hydroxyl as a nucleophile is electron-rich, so an attack on the electron-deficient part that the carbon caron and electron density is shifted towards the carboxyl oxygen, which gains a proton and forms hydroxyl as shown:

Nucleophilic addition reaction

When alkyl halide reacts with an alkene to form haloalkanes by breaking the unsaturation bond followed by carbocation formation, halide ion attacks on carbocation and forms haloalkanes as shown;

Electrophile addition reaction

Carbonyl is reduced to fro primary alcohol in the presence of lithium aluminium hydride by gaining the proton from aluminium hydride from alcohol as shown:

Carbonyl reduction

Alkene on the reaction from the alkane in the presence of hydrogen and palladium called linder’s catalyst, which is used to reduce the unsaturated bond to saturated bond as shown;

Reduction of alkene