The mean radius of the sun is 432,450 miles (696,000 kilometers), which makes its diameter about 864,938 miles (1.392 million km). You could line up 109 Earths across the face of the sun. The sun's circumference is about 2,713,406 miles (4,366,813 km). The total volume of the sun is 1.4 x 1027 cubic meters.
It was due to the metal foil in which the alpha particles can't even pass through. This experiment conducted by Rutherford led to the discovery of protons.
I think it goes like this.
mass = 78.6 g
molar mass = 60.1 g/mol
amount (in mols) = mass/mol
78.6 g / 60.1 g/mol = 1.30782 mol
^^rounded to 3 sig figs, final answer = 1.31mol
They are important because they are the electrons that help the atom to bond with another atom. They are in the outer most shell. ☺️