Chemistry Question...can anyone help PLEASE?!?!?

Question

Potassium dichromate, K2Cr2O7, is used in tanning leather, decorating porcelain and water proofing fabrics. Calculate the number of chromium atoms in 78.82 g of K2Cr2O7.

a) 9.490 × 1025 Cr atoms
b) 2.248 × 1024 Cr atoms
c) 1.124 × 1024 Cr atoms
d) 3.227 × 1023 Cr atoms
e) 1.613 × 1023 Cr atoms

Answer 1

Find the mol-wt of K2Cr2O7
Divide 78.82 g by that mol-wt to get moles
Multiply moles by Avagadro's #