What is the chemical formula of ferrous sulphate?

Q. (a) What is the colour of ferrous sulphate crystals? How does this colour change after heating?
​(b) Name the products formed on strongly heating ferrous sulphate crystals. What type of chemical reaction occurs in this change? Write chemical equation of the reaction.

Q. Dilute solution of ammonium hydroxide is added to aqueous solution of ferrous sulphate and ferrous hydroxide is formed. What type of reaction is this? Write chemical equation.

Q. The balanced chemical equation for the thermal decomposition of ferrous sulphate crystals is :

Q. Write the balanced chemical equation for the reaction $K_{2}C{r}_2{O}_7$ and Ferrous sulphate.