Number of atoms in one mole of substance = Avagadro's Number = 6.022 x 10^23.
Number of moles of a substance = Gram molecular/atomic weight divided by molar mass.
Number of moles in 100 gm of Sodium = 100/23 = 4.35.
Number of moles in 100 gm of Iron = 100/56 = 1.79.
Since number of moles of sodium is greater in 100gm, hence sodium has more number of atoms.
option A is correct

A) 100g of sodium would have more number of atoms.
Because the atomic weight of sodium is less than the atomic weight of Iron, it would require more sodium atoms to equate the mass with that of iron