Calculate the mass of 2.00 X 1020 molecules of SO3.

0.027g

Explanation:

From Avogadro's hypothesis, 1mole of any substance contains 6.02x10^23 molecules.

From the above, it means that 1mole of SO3 also contains 6.02x10^23 molecules.

1mole of SO3 = 32 + (16x3) = 32 + 48 = 80g

If 1 mole (80g) of SO3 contains 6.02x10^23 molecules,

Then Xg of SO3 will contain 2x10^20 molecules i.e

Xg of SO3 = (80x2x10^20)/6.02x10^23 = 0.027g