Change in concentration of a reactant is plotted against time and the slope dx/dt determined. The values of dx/dt are plotted against (a-x)2 and a straight line is obtained. It may be concluded that the reaction is:

Explanation

Option B is correct, indicating that the reaction is second order.When the rate of change of concentration with respect to time, dx/dt, is plotted against (a-x)2 (where 'a' is the initial concentration), and a straight line is obtained, it implies that the reaction follows second-order kinetics.This is a characteristic behavior of second-order reactions. In second-order reactions, the rate is directly proportional to the square of the concentration of a single reactant, which leads to a linear relationship when plotted against (a-x)2.Options A, C, and D are incorrect because they suggest different orders of reaction, which are not consistent with the observed behavior in this scenario.