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A radioactive element of mass 1g has half-life of 2 minutes, what fraction of the...

Chemistry
JAMB 2024

A radioactive element of mass 1g has half-life of 2 minutes, what fraction of the substance would have disintegrated after 10 minutes?

  • A. 1/4
  • B. 1/8
  • C. 1/16
  • D. 1/32
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Correct Answer: Option D
Explanation

\(\frac{Original mass}{2^n}\)  =   Residual mass

Where n = number of activity =  \(\frac{exposure  time}{half  life}\)

Given: 

Original mass = 1g, exposure time = 10 minutes , half life = 2 minutes, Residual mass = ?

Substituting all the given parameters appropriately, we have

                     n = \(\frac{10}{2}\)

                     n = 5

\(\frac{Original  mass}{2^n}\) =   Residual mass

\(\frac{1}{2^5}\)  =   Residual mass

\(\frac{1}{32}\)     =   Residual mass

Residual mass =  \(\frac{1}{32}\) or 0.03125g

There is an explanation video available below.


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Explanation Video

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