Answer:
Option D
Explanation:
Plan 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} decrease lineraly with time , thus it is zeroth order reaction w.r.t Q
$\frac{dx}{dt}=K[P]^{a}[Q]^{b}$
Order w.r.t P=a=1
Order w.r.t Q= b=0
Thus overall prder of the reaction
=1+0=1