Consider a reaction A + B + C. If the initial concentration of A was reduced from 4M to 2M in 1 hour and from 2M to 1M in 0.5 hours, the order of the reaction is
(2) For zero order reaction
K1 = x/t = 2/1 = 2M/h
K2 = x/t = 1/0.5= 2M/h
because, K1 and K2 are same. Hence, reaction follows zero order.