Question

Thallium-201 has a half-life 73 hours. If 4.0 mg of thallium-201 disintegrates over a period of 5.0 °, how many milligrams of thallium-201 will remain?

Answer 1

Given:

Half life of Thallium-201 (T1/2)= 73 hrs

Initial amount of thallium (A₀) = 4.0 mg

Disintegration Time period (t) = 5.0 hrs

To determine:

Amount of thallium remaining, A

Explanation:

The radioactive half-life (T1/2) can be related to the amounts of the radio active element through the relation:

A = $A_{0} e^{-0.693t/T1/2}$

A = 4.0 * $e^{-0.693*5/73}$ = 3.815 mg

Ans: Amount of thallium-201 remaining is 3.815 mg