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PHYSICS

JAMB 2009 - Question 47

Physics 2009 JAMB Past Questions - Question 47: A piece of radioactive material contains 102020 atoms.If the half life of the material is 20 seconds, the number of disintegration in the first second is?

Choose the correct answers from the options given.

A piece of radioactive material contains 102020 atoms.
If the half life of the material is 20 seconds, the number of disintegration in the first second is?

A: 3.47 x 10^18

B: 6.93 X 10

C: 3.47 X 10²

D: 6.93 X 10²

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Correct Answer

Explanation

The number of disintegration,?N in time interval At, is given by
- ?N = N?t
Where N is the number of atoms present at the time t
But ^ = (0.693)/T

= 0.693 ÷ 20

= 0.0347
∴ ?N = 0.0347 × 10^20

= 3.47 × 10^1 8