The number of atoms in 1 gram of iron are

One mol of iron Fe has $6.023\times {10}^{23}$ atoms.

It means that 56 g of iron has $6.023\times {10}^{23}$  atoms.

So, number of atoms present in 1 g of iron

    $\frac{6.023\times {10}^{23}}{56\text{g}}\times 1\text{g}=1.07\times {10}^{22}$