# Question #cf178

##### 2 Answers

It will never lose ALL of it.

#### Explanation:

After 1590 years it will have lost 50%

After 2x1590 years only 25% will be left

After 3x1590 years 12.5% will be left.

Etc.

Even after 10x1590=15900 years about 0.1% will be left.

The activity can be represented in a graph (NOT to scale):

graph{10*0.7^x [-4.02, 24.47, -4.12, 10.12]}

I got a finite value of

#### Explanation:

If we begin with

#A(t)=A_0e^(-0.693t/T_(1//2))#

where#T_(1//2)# is half life of the sample

For

Number of atoms in earth are estimated as

The isotope of radium which is being considered occurs in traces.

If we start with

Taking

we get a finite value of