Step-by-step explanation:
The amount of radioactive isotope remaining after n half-lives can be calculated using the following formula:
A = A0(1/2)^n
where A is the amount remaining after n half-lives, A0 is the initial amount, and 1/2 is the fraction remaining after each half-life.
In this case, we are given that the initial amount is 135 grams, and we want to know how much will be left after 4 half-lives. Therefore, we can substitute the given values into the formula and solve for A:
A = A0(1/2)^n
A = 135(1/2)^4
A = 135(1/16)
A = 8.44
Therefore, after 4 half-lives, approximately 8.44 grams of the radioactive isotope will be left.
