Ferrous sulphate heptahydrate is used to fortify foods with iron....

Formula of $ppm$ is as follow-

$ppm = \dfrac{weightofsolute}{weightofsolution} \times {10}^{6}$

$10 = \dfrac{MassofFe ( ing )}{100 \times 1000} \times {10}^{6}$
Or mass fe $= 1g$
$FeS{O}_{4} . 7{H}_{2}O\left(M = 278\right)$
56g in 1 mole
$1g - \dfrac{1}{56}mole$
$\dfrac{1}{56} \times 278g = 4.96g$

PPM is a concentration term and its full form is "parts per million" and it also can be expressed as milligrams per liter (mg/L). This measurement is the mass of a chemical or contaminate per unit volume of water.