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The half-life of a radioactive substance...

The half-life of a radioactive substance against `alpha-`decay is `1.2 xx 10^7 s`. What is the decay rate for `4 xx 10^15` atoms of the substance ?

A

`4.6 xx 10^(12)` atoms / s

B

`2.3 xx 10^(11)` atoms / s

C

`4.6 xx 10^(10)` atoms / s

D

`2.3 xx 10^(8)` atoms / s

Text Solution

Verified by Experts

The correct Answer is:
D
`(dN)/(dt) = - lamda N rArr |(dN)/(dt)| = (0.693)/(T_(1//2)) N`
`rArr (0.693)/(1.2 xx 10^(7)) xx 4 xx 10^(15)= 2.3 xx 10^(8)` atom/sec
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