A radioactive sample contains 2.2 mg of pure `._6C^(11)` , which has a half life period of 1224s. Calculate (i) number of atoms present initially. (ii) the activity when `5 mu g` of the sample will be left.

Answer

`1.2xx10^(20); 1.55xx10^(14)` disintegration/sec

Explanation

Here, number atoms present in 11 gram of sampel `=6.023xx10^(23)`
`:.` No. of atoms present in 2.2 mg of sample initially
`N_(0)=(6.023xx10^(23)xx2.2xx10^(-3))/11=1.2xx10^(20)`
No. of atoms present in `5 mug`
`N=(6.023xx10^(23)xx5xx10^(-6))/11=2.74xx10^(17)`
Activity of the sample
`A=lambdaN=0.693/TN=(0.693xx2.74xx10^(17))/1224`
`A=1.55xx10^(14)` disintegration/sec.