Question

In the reaction, P + Q $\to$ R + S, the time taken form 75% reaction of P is twice the time taken for 50% reaction of P. The concentration of Q varies with reaction time as shown in the figure. The overall order of the reaction is :

• A. 2
• B. 3
• C. 1

Answer 1

The correct option is C 1

Time of 75% reaction is twice the time taken for 50% reaction if it is first order reaction w.r.t P. From graph, [Q] decreases linearly with time, thus it is zeroth order reaction w.r.t Q.
$\frac{dx}{dt}=bk\left[P{]}^a\right[Q{]}^b$
Order w.r.t P = a = 1
Order w.r.t Q = b = 0
Thus, overall order of the reaction = 1 + 0 = 1