Question

Calculate the mass of 0.2 moles of oxygen molecules

Answer 1

molecular mass of O2 molecule = 32g/mol
mole = given wt/ molecular wt

0.2 = given wt/32

given weight = 32 × 0.2 = 6.4 g

Answer 2

Given,
Number of moles=  0.2

Molar mass of oxygen molecules= 32 g

Number of moles = given mass / molar mass
0.2= given mass/32

Mass of the object = 32 x 0.2
= 6.4g

hope it helps u..