Answer:
C. 2.
Explanation:
The total reaction order of this reaction is second order (2). For a second order reaction ,the rate depends on two variable concentration terms which may or may not be same.
Given that:
Two reactants combine to form a product in the reaction A + B → C
The above reaction is bimolecular as two molecules are involved in the reaction.
If
and
are the concentrations of A and B respectively at any time t, then assuming that the reaction is of first order with respect to both A and B , the overall order is second and the reaction rate is given by:

where;
= specific rate constant for a second order reaction and becomes the rate of the reaction when both
and
are unity.
D. The volume of a new substance has increased.
18 is 50% of 36
Like 36 divided by 2