What percentage of a radioactive substance remains after 7.00 half-lives have elapsed? 0.391%1.56%3.12%0.78%

Percentage of a radioactive substance remains after 7.00 half-lives have elapsed is 0.78%.

Explanation:

Formula used :

where,

A = amount of reactant left after n-half lives

= Initial amount of the reactant

n = number of half lives

We have:

n = 7.00

Percentage of a radioactive substance remains after 7.00 half-lives have elapsed:

=

the answer is option a.