Question

Question 1

Thallium-208 has a half-life of 3.00 minutes. How much of 80.0 g sample of Thallium-208 has decayed (no longer radioactive) after 12 minutes?

75,0 g
5.0 g
10.0 g
40,0 g

Answer 1

Step-by-step explanation:

Given:

T = 3.00 min

t = 12 min

m₀ = 80.0 g

____________

m - ?

The Law of radioactive decay:

m = m₀·2^(-t/T)

n = (t/T) = 12 / 3.00 = 4

m = m₀ / 2ⁿ

m = 80 / 2⁴ = 80 / 16 = 5 g