Number of atoms in 558.5 gram Fe is

Explanation:

Number of moles of Fe atoms = Mass ​/Atomic mass= 558.5/55.85 ​ =10

558.5 g of Fe corresponds to 10 moles of Fe and has 10NA ​ atoms of Fe.

Option A - 12 g of carbon means Avogadro's number, therefore, 60 g of carbon means, 5 moles of carbon and thus contains 5×NA ​ atoms, twice of this equals 10NA ​ atoms.

Option B - 10 NA ​ ​ atoms.

Option C - 8 g of He corresponds to 2 moles of He and thus, contains 2NA ​ atoms, half of the atoms will be NA ​ atoms of He.

Final Answer:

So, option A only corresponds to number of atoms in 558.5 g Fe, i.e. 10NA ​ atoms.