# Formula of green Vitriol oil is:A.$FeS{O_4} \cdot 7{H_2}O$B.$MgS{O_4} \cdot 7{H_2}O$C.$ZnS{O_4} \cdot 7{H_2}O$D.$CuS{O_4} \cdot 7{H_2}O$
We have to remember that the green Vitriol oil is salt of ferrous sulfate (or) iron (II) sulfate. These compounds are generally seen in heptahydrate but there are also various values of x. The formula of green vitriol is written as $FeS{O_4} \cdot 7{H_2}O$ . The hydrated form of this salt is used in the treatment of deficiency of iron and also for various industrial applications. The blue-green heptahydrate is the most general form of the material. We can use stain concrete and a few limestones and sandstone a yellowish rush colour. It is employed in the preparation of inks mostly iron gall ink. It is used in the textile industry as a fixation of dyes. It is also used in mushroom identification and as a catalyst of iron components of Fenton’s reagent. We can also do this in water purification by flocculation and for removal of phosphate in municipal and sewage treatment. It is one of the major components present in iron gall ink.
We need to know that the other states of hydration of iron (II) sulfates are $FeS{O_4} \cdot {H_2}O$ , $FeS{O_4} \cdot 4{H_2}O$ ,$FeS{O_4} \cdot 5{H_2}O$ , $FeS{O_4} \cdot 6{H_2}O$ . When iron (II) sulfates are dissolved in water, they give rise to aqua complexes that have octahedral molecular geometry and their magnetic behaviour is paramagnetic.