take 100g n2o mulitplied by (1/the mass of n2o) = your answer
the one stands for moles and you have to find the mass of n2o on the bottom, dont forget there is two nitrogens. i dont have a periodic table with me, sorry.
step 1
look up in the periodic table the atomic mass of Nitrogen and oxygen
Nitrogen = 14 g/mol, Oxygen = 16g/mol
so to find the atomic mass of N2O, you add them together so 14+14+16 = 44g/mol (you add 14 twice because there are two Nitrogen atoms)
step 2
set up like this
44g / 1 mol = 100 g / x mols
rewritten this is: 44x = 100
so solve it and x = 100/44 or 2.27 moles.