Can someone help me understand this please?

What are the charges of the subatomic particles by choosing the answer from the drop down menu. protons have a (+1,0,or-1). (protons,neutrons,electrons) have a 0 charge. 3.) electrons have a (+1,0,-1)

When balancing a chemical equation:

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.