A radioactive element gets spilled over the floor of a room. Its half life period is 30 days. If its initial activity is ten times the permissible value, after how many days will it be safe to enter the room?

Options

A. 100 days
B. 1000 days
C. 300 days
D. 10 days.

Answer

A

Explanation

a) Let the initial activity for safe working = A
`therefore` Initial activity `[A]_(0) = 10 A`
`k=0.693/30` days
`t=(2.303)/t log ([A]_(0))/([A])`
`t=(2.303 xx (30"days"))/(0.693) log 10`
`=99.6 ~~ 100` days.