Chemical kinetics

hydrogenation is a zero order reaction !
the rate of decrease of pressure is given by,
-dp /dt = k(pA^a) (pB^b )..........assuming that reaction occurs between A and B and (a) and (b) are the orders of the reaction wrt A and B respectively
,,,since this is a zero order reaction, a=b=0
=> k= rate constant =-dp/dt = 0.8 /50 = 0.016
.....hence rate of reaction (in this zero order reaction) =0.016