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Answer :

The half life of a nuclear element tells us the time it takes for a radioative material to reduce to half its value.

If the Initial amount is A_0,

then after 1 half life, remaining = 1/2 A_0

then after 2 half life, remaining = (1/2) 1/2 A_0 = 1/4 A_0

...

The half life equation is

[tex]A_t=A_0(\frac{1}{2^n}^{})[/tex]

A_0 is initial amount

n is the number of half lives that pass in interval "t"

A_t is the undecayed amount after time interval "t"

a)

Given half life is 138 days and

138 * 6 = 828 days

So,

6 half lives occur in 828 days

b)

The amount of Polonium in the sample is >>>>

[tex]\begin{gathered} A_t=A_0(\frac{1}{2^n}^{}) \\ A_t=60(\frac{1}{2^6}) \\ A_t=0.9375 \end{gathered}[/tex]

Rounded, that 0.94 grams

Correct Answer

A

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