The half-life of a radioactive isotope, X, is 2.00 years. How many years would it take a 4.000 g sample of X to decay and have only 0.500 g of X remain?

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

Which common material is an example of a polymer? (25 pts) a. steel b. plastic c. petroleum d. rubbing alcohol

An animal cell loses the ability to convert energy stored in food to energy that the cell can use. which of the cell's organelles has stopped working? a.the mitochondria b.the nucleus c.the vacuoles d.the endoplasmic reticulum