The initial concentration of a reactant in a first order reaction is 0.620 molar. What will be its

concentration after 3 half-lives?

a. 0.0388 M b. 0.310 M c. 0.0775 M d. 0.155M e. 4.96 M

thinkin c if not need a really good explaination of the real answer

c is right.

To determine the concentration of a reactant after a certain number of half-lives in a first-order reaction, we can use the formula:

Concentration = Initial concentration * (1/2)^(Number of half-lives)

In this case, the initial concentration of the reactant is 0.620 M. We are asked to find the concentration after 3 half-lives.

First, we need to calculate (1/2)^(Number of half-lives):

(1/2)^(3) = 1/8 = 0.125

Now, multiply the initial concentration by the calculated value to find the concentration after 3 half-lives:

Concentration = 0.620 M * 0.125 = 0.0775 M

Therefore, the concentration of the reactant after 3 half-lives is 0.0775 M, which corresponds to option c.