Question

How many numbers numbers of atom contain 2 gram of oxygen??

Answer 1

16 g of O have atoms = 6.022×10²³
2 g of O have atoms = 6.022 ×10²³×2/16
= 7.5275 ×10²²

Answer 2

Oxygen=2g
Atomic mass=16×2=32g
So moles= 2/32=1/16moles
Now atomic no.=moles × avagadro no. × atomicity.
Atoms=1/16 × 6.022×10^23 × 2
=0.752×10^23
=7.52×10^22