What is the mass (in grams) of 9.09x10^24 molecules of methanol (CH3OH) ?

AND

How many moles of N are in 0.183g of N2O?

The amount of a substance can be converted into grams of that substance by using the molar mass. It is a physical property of a substance which describes the mass per mole of the substance. The molar mass of CH3OH is 32.04 g / mol. Multiplying the given amount of CH3OH with the molar mass will yield to the mass of the substance.

9.09x10^24 molecules CH3OH (1 mol / 6.022x10^23 molecules) (32.04 g/mol) = 483.63 g CH3OH

Dividing the molar mass of N2O which is 44.08 g/mol to the given amount will yield to the number of moles.

0.183 g N2O / 44.08 g / mol = 0.0042 mol N2O