Molar mass problems?

Question

How do you convert the following:
grams to moles
moles to grams
atoms to moles

Answer 1

a. Use the formula: n = m/Mr, where m the mass in grams, Mr the molar mass of the substance and n the number of moles.

b. Solve the above for m: m = n*Mr

c. Divide the number of atoms N by the Avogadro's number Na = 6.023*10^(23): n = N?Na

Answer 2

1- moles of Na = grams of Na/atomic weight of Na

2- grams of Na = atomic weight of Na*moles of Na

3- 1 mole= No. Avogrado atom
? mole = 100 atom

so,
100 atom/No. avogrado = ? mole