A certain radioactive element disintegrates with a decay constant of `7.9 xx 10^(-10) //s` At a given instant of time, if the activity of the sample is equal to `55.3 xx 10^(11)` disintegration/second then number of nuclei at that instant of time ia

Options

A. `7.0 xx10^(21)`
B. `4.27xx10^(13)`
C. `4.27 xx10^(3)`
D. `6xx10^(23)`

Answer

A

Explanation

Decay constant,
`lambda=7.9xx10^(-10)//sec`
`A=55.3xx10^(-11)` disintegration/sec
`A=lambbda N`
`rArr N=(A)/(lambda)=(55.3xx10^(11))/(7.9xx10^(-10))=7xx10^21`
`7.0xx10^21`.