How many years will it take for 88g tritium to decay to an 11g sample?

2 answers

k = 0.693/t1/2
Look up the value of half-life in your text or notes (or tables on the Internet).
Then ln(No/N) = kt
No = 88 g
N = 11 g
k = from above.
Solve for t.
Solve for t.