Question

Number of atoms in 558.6 g Fe (atomic mass = 55.86 g/mol) is:

• A. Twice that in 60 g Carbon
• B. $6.023\times {10}^{22}$
• C. Half that of 8 g He
• D. $558.6\times 6.023\times {10}^{23}$

Answer 1

The correct option is A Twice that in 60 g Carbon

Number of atoms = $n\times N_A=\frac{\text{given mass}}{\text{molar mass}}\times N_A=\frac{558.6}{55.86}\times 6.02\times {10}^{23}=10\times 6.02\times {10}^{23}$
Number of atoms in 60 g C = $5\times 6.02\times {10}^{23}$ atoms
$\therefore$ the number of atoms in 558.6 g of Fe = twice the number of atoms in 60 g C.