1. an alpha particle
gamma rays are formally massless, positrons and electrons (beta particles) have negligible mass, but alpha particles have about 4 amu of mass
Answer:
584.2 g
Explanation:
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In this case, since we know the 20% of the atoms correspond to sodium, we can compute the total atoms as shown below:

Which are also equal to 1 mol and the Avogadro's number of sodium chloride with a molar mass of 58.44 g/mol; thus, the grams of salt turn out to be:

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Facts about Pumice:
The lightest rock on earth.
Formed in Molten Lava.
Most of the earths crust is made from rocks such as Pumice (Igneous Rocks).
Contains many minerals that help plants to grow.
Facts about Sandstone:
It can form on land or in the sea.
It has been used as far back as prehistoric times to make house ware items and shelter contruction.
They can take thousands of years to form.
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