Question

A pale green crystalline metal salt of $\left(X\right)$ dissolves freely in water. It gives a brown precipitate on the addition of $aq.NaOH$. The metal salt solution also gives a black precipitate on bubbling $H_{2}S$ in aqueous medium. An aqueous solution of the metal salt decolorizes the pink color of the permangnetic solution. The metal in the metal salt solution is:

• A. $Fe$
• B. $Pb$
• C. $Cu$
• D. $Al$

Answer 1

Answer: (A)

$Fe$

The metal in the metal salt solution is iron (Fe).

$2NaOH+FeS{O}_4\to Fe(OH{)}_2$ (Brown) $+N{a}_{2}S{O}_4$

$Fe(OH{)}_2+H_{2}S\to FeS$ (black) $+2H_{2}O$

$8H_{2}S{O}_4+2KMn{O}_4$(pink) $+10FeS{O}_4\to 5F{e}_2(S{O}_4{)}_3+2MnS{O}_4+K_{2}S{O}_4+8H_{2}O$

Here pink color after reaction has been decolorised.