Hemoglobin contains \( 0.34\% \) of iron by mass, The number of Fe atoms in \( 3.3 \, \text{g} \) of hemoglobin is. (Given Atomic mass of Fe is \( 56 \, \text{u} \), \( N_A = 6.022 \times 10^{23} \, \text{mol}^{-1} \))
\( 1.21 \times 10^5 \)
\( 12.0 \times 10^{16} \)
\( 1.21 \times 10^{20} \)
\( 3.4 \times 10^{22} \)