The disintegration rate of a certain radioactive sample at any instant is 4250 disintegrations per minute. 10 minutes later, the rate becomes 2250 disintegrations per minute. The approximate decay constant is (Take log e 1 . 88 = 0 . 63 )

Step-by-step solution

At t = 0 disintegration rate A 0 = 4250   dpm At t = 10   min disintegration rate A t = 2250 dpm The activity of a sample at any time is given by, A t = A 0 e - λ t ⇒ 2250 = 4250 e - λ 10 ⇒ 10 λ = ln 4250 2250 = ln 1 . 88 ⇒ λ = 0 . 063   min - 1