(i) 1 molecule of methane contains 10 electrons (6 from carbon, 4 from hydrogen)
Therefore, 1 mole of methane contains 10*NA = 6.022*1024 electrons.
(ii) Number of neutrons in 14g (1 mol) of 14C = 8*NA = 4.817*1024 neutrons.
Number of neutrons in 7 mg (0.007g) = (0.007/14)*4.817*1024 = 2.409*1021 neutrons.
Mass of neutrons in 7 mg of 14C = (1.67493*10-27kg)*(2.409*1021) = 4.03*10-6kg
(iii) Molar mass of NH3 = 17g
Number of protons in 1 molecule of NH3 = 7+3 = 10
Therefore, 1 mole (17 grams) of NH3 contains 10*NA = 6.022*1024 protons.
34 mg of NH3 contains (34/1700)*6.022*1024 protons = 1.204*1022 protons.
Total mass accounted for by protons in 34 mg of NH3 = (1.67493*10-27kg)*(1.204*1022) = 2.017*10-5kg.
