What is the difference in mass between 3.01×10^24 atoms of gold and a gold bar with the dimensions 6.00 cm x 4.25 cm x 2.00 cm

The difference in mass between 3.01×10^24 atoms of gold and a gold bar with the dimensions 6.00 cm X 4.25 cm X 2.00 cm is :

Difference  in mass = 985.32 - 984.5 = 0.82 g

Explanation:

Part I :

n = 4.9983

n = 4.99 moles

(Note : You can also take n = 5 mole )

Molar mass of gold = 196.96 g/mole

This means, 1 mole of gold(Au) contain = 196.96 grams

So, 4.99 moles of gold contain = g

4.99 moles of gold contain = 984.8 g

Mass of atoms of gold = 984.5 g

Part II :

Density of Gold =

Volume of the cuboid =

Volume of the gold bar =

Volume of the gold bar = 51

Using formula,

Mass = 985.32 g

So, A  gold bar with the dimensions 6.00 cm X 4.25 cm X 2.00 cm has mass of 985.32 g

Difference  in mass = 985.32 - 984.5 = 0.82 g

where are the choice options?

the answer is 75.0%.