`.^(90)Sr` shows `beta`activity and its half life period os 28 years. What is the activity of a sample containing 1 g of `.^(90)Sr`?

Explanation

Activity = No. of atoms disintegration per second
`= lambda xx` Total number of atoms
`lambda = (0.693)/(28 xx 365 xx 24 xx 60 xx 60)`
The number of atoms in 1g of `.^(90)Sr = ( 6.023 xx 10^(23))/(90)`
Activity `= (0693)/(28 xx 365 xx 24 xx 60 xx 60) xx (6.023 xx 10^(23))/(90)`
`= 5.25 xx 10^(12)` disintegrations per second
`= (5.25 x 10^(12))/(3.7 xx 10^(10)) = 141.89` curie