Question

 If 80mg of a radioactive element decays to 10 mg in 30 mins., what is the element's half-life in minutes?
a- 10  b- 20  c- 30  d- 40

Answer 1

Answer:

the answer is a.10

Explanation:

in(No/N) = kt

No = 80 mg

N = 10 mg

t = 30 min

solve for k, then

k = 0.693/t1/2

Substitute k from above and solve for t1/2

10 min is correct.