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A piece of radioactive material contains 10\(^{20}\) atoms. If the half life of the material...

Physics
JAMB 2009

A piece of radioactive material contains 10\(^{20}\) atoms.
If the half life of the material is 20 seconds, the number of disintegration in the first second is?

  • A. 3.47 x 1018
  • B. 6.93 x 10 20
  • C. 3.47 x 1020
  • D. 6.93 x 1018
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Correct Answer: Option A
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 \(\times\) 10\(^20\)

= 3.47 \(\times\) 10\(^18\)

There is an explanation video available below.


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Explanation Video

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WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts