i)Pyrolysis: The decomposition of a compound by heat is called pyrolysis. Large alkane molecules are broken down to give lower molecular weight alkanes, alkenes and hydrogen.
Eg: When ethane is heated to 500 0C in the absence of air, it gives a mixture of methane, ethylene and hydrogen.
C2H6 → C2H4 + CH4 + H2
ii)Hydration: It refers to a unit process of adding a water molecule to an Organic Compound.
Hydration of Ehtylene :
Ethanol can be produced by hydration of ethylene in presence of a phosphoric acid at about 300oC
Or any other example student can write
iii)Hydrogenation: It refers to the chemical reaction of an organic compound with molecular hydrogen in the presence of a catalyst.
Chemical Reaction for hydrogenation:
CH2= CH2 + H2 → CH3-CH3
C6H6 + 3H2→C6H12