How many potassium atoms in 7.50g of potassium chromate?
mols K2CrO4 = grams/molar mass = ?
# mols K atoms/molecule = 2x that.
Then 1 mol conains 6.02E23 atoms. You have x atom, so .......
# mols K atoms/molecule = 2x that.
Then 1 mol conains 6.02E23 atoms. You have x atom, so .......