30gC2H6 produce ⟶3mol of H2O3gC2H6 produce ⟶0.3mol of H2O Now, mole of ethane =
3g
30gmol−1
=0.1mol Hence, 0.1 mol of ethane gives =03NA molecules of water =0.3×6.023×1023 molecules of H2O =18.06×1022 =18×1022 Thus, ethane gives 18 molecules of H2O.