Question

Calculate the number of electrons in a sample of nitrogen gas(N2) which weighs 5.6 grams.(gram molecular mass of nitrogen is 28)

Answer 1

No of moles of N2 gas=given weight/molecular weight
=5.6/28
=0.2 moles
1 mole of Nitrogen contains Avogadro number (6.023*10^23) of Nitrogen molecules.
0.2 moles of nitrogen contains 0.2*6.023*10^23 molecules=1.204*10^23 molecule.

1 molecule of Nitrogen contains 14 electrons.
1.204*10^23 molecule contains 14*1.204*10^23 electrons=16.856*10^23 electrons.