The halftime of radio active isotope is the time it takes for a quantity of the isotope to be reduced to half is initial mass starting with 160 g of a radioactive isotope how much will it be left after three half-lives

pay attention in your classes and concentrate the best thing you can do to raise your test scores is to pay attention when you're supposed to be learning the material: in class!

take good notes.

do your homework.

use mnemonics and other tricks.

do practice tests.

note: the best i know.