What is the pyrolysis of alkane? Give reaction.

Definition: Higher alkanes,on heating to a high temperature,decompose into lower alkanes,alkenes,etc. Such a decomposition reaction into smaller fragments by the application of heat is called pyrolysis or cracking.
General reaction:
$Higher \ alkane \xrightarrow[Pyrolysis]{Temperature} Lower \ alkane + Alkene \ mixture$
Example: Pyrolysis of hexane $(C_6H_{14})$ at $773 \ K$:
$C_6H_{14} \xrightarrow{773 \ K} C_6H_{12} + H_2$ $(i)$
$C_6H_{14} \xrightarrow{773 \ K} C_4H_8 + C_2H_6$ $(ii)$
$C_6H_{14} \xrightarrow{773 \ K} C_3H_6 + C_2H_4 + CH_4$ $(iii)$
Mechanism: Pyrolysis of alkanes is believed to be a free radical reaction. The preparation of oil gas or petrol gas from kerosene oil or petrol involves the principle of pyrolysis. For example,dodecane $(C_{12}H_{26})$,a constituent of kerosene oil,on heating to $973 \ K$ in the presence of platinum,palladium,or nickel,gives a mixture of heptane and pentene.
$C_{12}H_{26} \xrightarrow[973 \ K]{Pd, Pt, Ni} C_7H_{16} + C_5H_{10} + \text{Other products}$