# One of the important use of ferrous sulphate is in the

$\begin{array}{1 1}(a)\;\text{Manufacture of blue black ink}\\(b)\;\text{Preparation of hydrogen sulphide}\\(c)\;\text{Manufacture of chalks}\\(d)\;\text{Preparation of anhydrous ferric chloride}\end{array}$

One of the important use of ferrous sulphate is in the manufacture of blue black ink.
Hence (a) is the correct answer.