A sample of radioactive element has a mass of 10 g at an instant t = 0. The approximate mass of this element in the sample after two mean lives is
- 1.35 g
- 2.50 g
- 3.70 g
- 6.30 g
Answer
(1) 1.35 g
Solution
m = m0 e- t and mean life = 1
⇒ For t = 2 : t = 2
⇒ m = 10 e-2
= 107.389
1.35 g
Answer: (1)