Question

In the reaction, P + Q ⟶ R + S

the time taken for 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

Overall order of reaction can be decided by the data given $t_{75﹪}=2t_{50﹪}$

∴ It is a first order reaction with respect to P.

From graph [Q] is linearly decreasing with time, i.e., order of reaction w.r.t. Q is zero and the rate expression is $r=\left[P{]}^1\right[Q{]}^0.$

Therefore 1 is the right answer.