Neon has three stable isotopes. Neon-20 has an atomic mass of 19.992 u and makes up 90.48 % of the…

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Neon has three stable isotopes. Neon-20 has an atomic mass of $19.992$ u and makes up $90.48\ \%$ of the atoms. Neon-21 has $20.994$ u and $0.27\ \%$ . Neon-22 has $21.991$ u and $9.25\ \%$ . Find the average atomic mass of neon. How many neon-22 atoms are there in a sample of $10\,000$ atoms?

Need a reminder? The key ideaShow

A nucleus of mass number $A$ has a radius $R = R_0A^{1/3}$ with $R_0 = 1.2$ fm, and $1\ \text{fm} = 10^{-15}$ m. Its mass is about $A$ atomic mass units, with $1\ \text{u} = 1.660539 \times 10^{-27}$ kg. The density is the mass over the volume $\tfrac{4}{3}\pi R^3$ , and it is the same for every nucleus.

The worked solution

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