How many atoms are in 6.9 mol Zn?

              4.155 × 10²⁴ Atoms

Explanation:

Formula used,

Number of Atoms = Moles × 6.022 × 10²³ Atoms.mole⁻¹

Putting value of moles,

Number of Atoms = 6.90 mole × 6.022 × 10²³ Atoms.mole⁻¹

Number of Atoms = 4.155 × 10²⁴ Atoms

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)