Ans: (D)
Number of atoms of \(\mathrm{Ag}=\frac{1}{108} \times \mathrm{N}_{\mathrm{A}}=0.009 \mathrm{~N}_{\mathrm{A}}\)
Number of atoms of \(\mathrm{Fe}=\frac{1}{56} \times \mathrm{N}_{\mathrm{A}}=0.0178 \mathrm{~N}_{\mathrm{A}}\)
Number of atoms of \(\mathrm{Cl}_{2}=\frac{1}{71} \times 2 \times \mathrm{N}_{\mathrm{A}}=0.028 \mathrm{~N}_{\mathrm{A}}\)
Number of atoms of \(\mathrm{Mg}=\frac{1}{24} \mathrm{~N}_{\mathrm{A}}=0.041 \mathrm{~N}_{\mathrm{A}}\) [largest]