What mass of oxygen contains the same number of molecules as 42g of nitrogen?

Given: 42 g of N2

Solve for O2 mass that contains the same number of molecules to 42 g of N2.

Solve for the number of moles in 42 g of N2

1 mole of N2 = (14 * 2) g = 28 g so the number of moles in 42 g of N2 is equal to 42 g / 28 g per mole = 1.5 moles

Solve for mass of 1 mole of oxygen

1 mole of O2 = 16 g * 2 = 32 g per mole

Solve for the mass of 1.5 moles of oxygen

mass of 1.5 moles of O2 = 32 g per mole * 1.5 moles

mass of 1.5 moles of O2 = 48 g

So 48 g of O2 contains the same number of molecules as 42 g of N2

it's c. elements are placed in rows based on how may valencies electrons have.