The comparison of the number of atoms in a copper coin the size of a penny with the number of people on earth is used to
illustrate which of the following:
that atoms are indivisible
that atoms are very small
that atoms are very large
thatina copper penny, there is one atom for every person on earth

Probably it was ment to illustrate how significant and indivisible, being very small, atoms are and how each of them under normal conditions of presure and temperature find their own place eventually

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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