Question

How much of a 500g sample of potassium-42 is left after

Answer 1

Answer:

15.625 g of a 500 gram sample of potassium-42 with 12.4 hours of Half -life is left after 62 hours.

The half-life is the time after which half of the initial quantity of a radioactive substance is left .

Given here,

The half-life of K-42 = 12.4 hours

The initial quantity of K-42 = 500 gm

The final quantity after 62 hours = ?

The number of half cycle

\bold { = 62\times \dfrac 1{12.4} = 5,}=62×

12.4

1

=5,

Thus the number of half life cycles in 62 hours is 5,

After 1 half life \bold {= \dfrac {500}{2} = 250}=

2

500

=250

After 2 half lives \bold {= \dfrac {250}{2} = 125}=

2

250

=125

After 3 half lives \bold {= \dfrac {125}{2} = 62.5}=

2

125

=62.5

After 4 half lives \begin{gathered}\bold {= \dfrac {62.5}{2} = 31.25}\\\end{gathered}

=

2

62.5

=31.25

After 5 half lives \begin{gathered}\bold {= \dfrac {31.25}{2} = 12.625}\\\end{gathered}

=

2

31.25

=12.625

15.625 g of a 500 gram sample of potassium-42 with 12.4 hours of Half -life is left after 62 hours.

To know more about Half life,

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