If a rock initially contained 10 milligrams of a radioactive substance when it first formed, how much remains after 4 half-lives?

May someone me with these science questions

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.

Select the correct answer a modure consists of glucose and water. what is the percent composition of glucose in the mixture if it contains 1.3 moles of glucose (cho total mass of the mature is 276 grams? ) and the a 1775