Answer:
[tex]\dfrac{1}{2}[/tex]
Explanation:
Let assume that X and Y are the reactants of a given reaction.
Then the rate can be expressed as:
rate = k[X][Y]
Suppose the concentration of X is quadrupled and the rate is doubled.
Then. we have;
[tex]2 \times rate = k[4X]^{\dfrac{1}{2}} [Y][/tex]
So, the initial rate of the concentration will be [tex]\dfrac{1}{2}[/tex] when the concentration of the reactant is increased by a factor of two.