How many moles of atoms are there in 4.1x10^-12 g O?

Hey there

Molar mass of O is 16 g/mol.

Divide 4.1 x 10⁻¹² by 16.

(4.1 x 10⁻¹²) ÷ 16

2.6 x 10⁻¹³

There are 2.6 x 10⁻¹³ moles of O in 4.1 x 10⁻¹²g of O.

Hope this helps!

c is the answer because when something is left after something evaporates that shows the chemical change.