- #1

songoku

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## Homework Statement

The radioactive isotope radon-222 may decay spontaneously by emitting an alpha particle. The daughter nucleus is an isotope of polonium. The atomic masses of these isotopes are:

Rn-222 : 222.0157 u

Po : 218.00896 u

He : 4.00260 u

A sample of radon-222 contains 3.0 x 10

^{7}nuclei. The total energy that will be release in a time interval of 3 T

_{1/2}through alpha decay of the radon-222 is:

a. 3.856 MeV

b. 5.785 x 10

^{7}MeV

c. 8.677 x 10

^{7}MeV

d. 1.012 x 10

^{8}MeV

e. 1.085 x 10

^{8}MeV

## Homework Equations

E = mc^2

T

_{1/2}= (ln 2) / λ

## The Attempt at a Solution

If the question asks only for one half-life then the energy released = (mass of Rn - mass of Po - mass of He) x 931.5 MeV. Is this correct?

I don't know how the time interval of 3 half-life and number of nuclei play part in this question. Are they used to find energy released or they are only redundant information?

Thanks