PLEASE HELP I WILL GIVE 30 POINTS PLEASEDEE

Asample of radium-226 will decay 1/4 of its original amount after 3200years. what is the half-life of radium-226?

In order to calculate the amount of heat transferred you must know the __ and specific heat of the material, as well as the change in temperature. a. volume b. density c. mass d. enthalpy

How many atoms of mg are present in 97.22 grams of mg? 6.022 × 1023 2.408 × 1024 4.818 × 1024 5.855 × 1025