Question

Actinium-226 has a half-life of 29 hours. If 10g of actinium-226 disintegrates over a period of 145 hours,

how many mg of actinium-226 will remain?
a. 0.3125mg
c. 31.25mg
b. 3.125mg
d. 312.5mg

Answer 1

Answer: d) 312.5 mg

Step-by-step explanation:

This problem can be solved using the Radioactive Half Life Formula:

`A=A_(o).2^{(-t)/(h)}`

Where:

`A` is the remaining amount of Actinium-226

`A_(o)=10 g` is the initial amount of Actinium-226

`t=145 h` is the time elapsed

`h=29 h` is the half life of Actinium-226

Knowing this, let's find
`A`:

`A=(10 g) (2)^{(-145 h)/(29 h)}`

`A=0.3125 g (1000 mg)/(1 g)=312.5 mg`