\(\mathrm{ppm}=\frac{\text { wt. of Fe }}{\text { wt. of wheat }} \times 10^{6}\)

let the wt. of salt be \(=\mathrm{w} \mathrm{gm}\)

moles \(=\frac{\mathrm{w}}{277.85}\)

wt. of \(\mathrm{Fe}=\left(\frac{\mathrm{W}}{277.85} \times 55.85\right) \mathrm{gm}\)

\(10=\frac{\frac{\mathrm{W}}{277.85} \times 55.85}{10^{5}} \times 10^{6}\)

\(W=\frac{277.85}{55.85}=4.97\)