Halflife is the time needed for a radioactive molecule to decay half of its current mass. If t is the time elapsed, the formula for the halflife would be:
final mass= original mass * [tex]\frac{1}{2} ^{\frac{t}{halflife} [/tex]
If you put the information of the problem into the formula, the equation will be:
final mass= original mass * [tex]\frac{1}{2} ^{\frac{t}{halflife} [/tex]
final mass= 800g * [tex]\frac{1}{2} ^{\frac{t}{16 min} [/tex]