Answer: 82.0 g/mole
Explanation:
Use the units to see that if we divide 1.64 grams by 0.0200 moles, we'll get a number that is grams/mole, the definition of formula mass.
1.64/0.0200 = 82.0 g/mole (3 sig figs)
We can't tell from this alone what the molecular formula might be, but C6H10 (cyclohexene) comes close (82.1 grams/mole).
Copper (I) oxidation state is 1 Cu2So4
copper (II) oxidation state is +2 CuSo4
copper (i) also give up one electron so you need two of them to react with the sulfate ion (which has charge of -2)
and also all metallic ions have an multiple oxidation levels corresponding to the number of electrons they can exchange or loose
Hope this helps
and D. to identify minerals
because it has ns1 electron configuration like the alkali metals