Question

what is the total number of electrons present in 1.6 gram of Methane?

Answer 1

 You need to use the periodic table. C has atomic number 6 so each C atom has 6 electrons and H has atomic number 1 so each H atom has 1 electron. Each CH4 molecule will have 6 + 4(1) = 10 electrons. 

moles CH4 = 1.6 g(1 mole CH4)/(16.0 g CH4) = 0.10 mole CH4 

Now, remember that each mole of molecules (or of anything else) will have 6.022 x 10^23 molecules. 

No. electrons = (10 electrons/CH4 molecule)(6.022 x 10^23 molecules/mole)(0.10 moles of CH4) 

Total number of electrons will be 6.022 x 10^23 electrons