The half life of the nuclide `Rn^(220)` is` 54.5` sec. What mass of radon is equivalent to 1 millicurie.

Answer

`1.06 xx 10^(-15)`

Explanation

`A=Nlambda`
` 1xx10^(-3) xx3.7 xx10^(10)` d.p.s `=Nxx(0.693)/(54.5) " " ` 1curie`=3.7 xx 10^(10)` d.p.s.
`N=290.98 xx10^(7) rArr (N)/(N_(A))=(29.98 xx10^(7))/(6.023 xx10^(23))=48.31 xx 10^(-16)` moles
Mass of Rn`=220 xx48.31 xx 10^(-16)`
`rArr 10628.56 xx 10^(-16)` gm
`rArr 1.062 xx 10^(-12)gm rArr (1.06 xx 10^(-12))/(1000)kg rArr 1.06 xx 10^(-15) kg`