Answer:
It will be left 11 grams of the radioactive isotope after four half-lives
Step-by-step explanation:
Let's calculate the first four half-lives of the radioactive isotope, this way:
1. First half-life:
170 * 0.5 = 85 grams
2. Second half-life:
85 * 0.5 = 42.5 grams
3. Third half-life:
42.5 * 0.5 = 21.25 grams
4. Fourth half-life:
21.25 * 0.5 = 10.625 grams = 11 grams (Rounding to the nearest gram)
