total 5 atoms
2 of Mg and 3 of O
one atom
NO2 = 3 atoms.
4
There is no CuSO. If you mean CuSO4, it would be 6 atoms per formula unit; one Cu atom, one S atom, and 4 O atoms.
2H +1S +4O = 7
One you idiot it's an element Au
Borax (Na2B4O7) has two sodium atoms in the formula unit.
Cl2 is a molecule formed of 2 atoms of Chlorine.
Sand is silicon dioxide, formula SiO2
Sodium oxide is made up of three atoms: two sodium atoms and one oxygen atom.
It takes three helium atoms to create one carbon atom through nuclear fusion in stars.
Silicon dioxide is a molecule made of one silicon and two oxygen for a total of three atoms.