Question

The half-life of a radioactive isotope is the time it takes for a quantity of the isotope to be reduced to half its initial mass. Starting with 220 grams of a radioactive isotope, how much will be left after 5 half-lives?

Answer 1

Answer:

$\boxed{6.875 \text{\: grams}}$

Step-by-step explanation:

Half-lives are how long it takes for half of a substance to decay. If you start with a certain amount and it decays for a certain amount of half-lives, you are dividing by $2^{x}$, where x  is equal to the amount of half-lives.

In order to solve this question, simply divide the starting value by 2 raised to the value of half-lives.

$\large\boxed{\frac{220}{2^{5}}=6.875\text{\: grams}}$