To determine the number of moles(n) of a substance, divide its amount given in grams by the molar mass. The element in the problem is gold (Au) which has a molar mass of 196.97 grams per mole. The division is better illustrated below
n = 35.12 g / 196.97 grams per mole
The answer to the operation above is 0.1783 moles. Therefore, there are approximately 0.1783 moles of Au in 35.12 grams.
