Question

Suppose you had a sample containg 20 g of a parent isotope. After how many half-lives would less than 2 g of the parent isotope remain?

Answer 1

the isotope are originally present, then only 50 grams will remain after 8 minutes, 25 grams after 16 minutes

Answer 2

\[\large 2^L \cdot m_1 = m_0\]

Do you know anything about logarithms? (What grade level is this?)

Answer 3

9th

Answer 4

@cupcake918 Where did you get "minutes" from...?

Answer 5

After one half life, the mass is cut in half.

\[\textrm{After 1 half life: }\ \ {20 \over 2} \\ \textrm{After 2 half lives: }{20 \over 2\cdot2} \\ \textrm{After 3 half lives: }{20 \over 2\cdot2\cdot2} \\ \textrm{After 4 half lives: }{20 \over 2\cdot2\cdot2\cdot2}\]

Answer 6

Keep doing that until you get an answer less than \(2 \ \textrm{grams}\).