To figure out the number of moles, we just need to divide the amount of grams by the molar mass of gold which is 196.97.
2.7*10^-10 g Au / 196.97 g/mol = 1.37076712*10^-12 mol Au
Then we look at the significant figures. Having started with two, the answer must have two figures. Make sure to round the last digit.
1.4*10^-12 mol Au
To figure out the number of moles, we just need to divide the amount of grams by the molar mass of gold which is 196.97.
2.7*10^-10 g Au / 196.97 g/mol = 1.37076712*10^-12 mol Au
Then we look at the significant figures. Having started with two, the answer must have two figures. Make sure to round the last digit.
1.4*10^-12 mol Au