Consider the decomposition of cumene to form benzene and propylene

C$6$H$5$CH$($CH$3)2->$ C$6$H$6+$ C$3$H$6$

Nomenclature to be used: C $=$ cumene, B $=$ benzene, P $=$ propylene

C $+$ S $$ C$$S Adsorption of cumene

C$$S $$ B$$S $+$ P Surface reaction

B$$S $$ B $+$ S Desorption of benzene from the surface

Derive an expression considering:

Surface reaction is the rate$-$limiting step

Adsorption is rate$-$limiting step

Desorption is the rate$-$limiting step