What is the total mass of 3.01 x 10^23 atoms of helium gas?

Answer;

2 g

Explanation;

Moles of atom = atoms / 6.022 * 10^23

Therefore; number of moles;

= (3.01 * 10^23) / (6.022 * 10^23)

= 0.5 moles

But;

Mass = moles of atom * Molar Mass of Helium

Thus total mass of helium:

= 0.5 * 4

= 2 g