Question

A pale green crystalline metal salt of $M$ dissolves freely in water. On standing it gives a brown ppt. on addition of aqueous $NaOH$. The metal salt solution also gives a black ppt. on bubbling $H_{2}S$ in basic medium. An aqueous solution of the metal salt decolourizes the pink colour of the permanganate solution. The metal in the metal salt solution is :

• A. Copper
• B. Aluminium
• C. Lead
• D. Iron

Answer 1

The correct option is D Iron

The metal in the metal salt solution is iron.
The pale green crystalline metal salt is ferrous sulphate. It dissolves freely in water. On standing it gives a brown ppt. of basic ferric sulphate $Fe\left(OH\right)\left(S{O}_4\right)$
$4FeS{O}_4+2H_{2}O+O_2\to 4Fe\left(OH\right)\left(S{O}_4\right)$
The metal salt solution also gives a black ppt. on bubbling H2S in basic medium.
An aqueous solution of the metal salt decolourizes the pink colour of the permanganate solution.
$2KMn{O}_4+8H_{2}S{O}_4+10FeS{O}_4\to K_{2}S{O}_4+2MnS{O}_4+5F{e}_2(S{O}_4{)}_3+8H_{2}O$