Question

How much will Avagadro's number of chlorine atoms weigh

Answer 1

Divide the number of atoms(6.022*1023) by avogadros number (6.022*1023), the resulting number(1) is the number of moles you have. Multiply the number of moles of atoms(1) by the molar mass of chlorine(35.5) and the answer is how many grams(35.5g) of the substance you have.
n(Cl)=6.022*1023/6.022*1023=1 mol
m(Cl)=n(Cl)*M(Cl)=1mol*35.5g/mol=35.5g