Question

Consider the following data and then calculate the half-life for this particular isotope:
Time Activity (cpm)
0 days 320,000
40 days 216,100
100 days 120,000
(A) 35.2 days.
(B) 75.6 days.
(C) 70.6 days.
(D) 62.9 days.
(E) None of these.

Answer 1

Answer:

D. 62.9 days

Explanation:

Half Life Cpm activity:

320,000 / 2 = 160,000

At 100 days cpm is 120,000 then cpm 160,000 will be at 62.9 days.

[320,000 - 216,100] / 40 days = 2,597.5

160,000 / 2,597.5 = 62.9 days.