Question

The metal hydroxide which is soluble in excess of ammonium hydroxide:

• A. $Fe(OH{)}_2$
• B. $Fe(OH{)}_3$
• C. $Cu(OH{)}_2$
• D. $Al(OH{)}_3$

Answer 1

The correct option is C $Cu(OH{)}_2$

The metal hydroxide which is soluble in excess of ammonium hydroxide is $Cu(OH{)}_2$. It forms soluble complex tetramminecupric hydroxide $\left[Cu\right(N{H}_3{)}_4\left]\right(OH{)}_2$.
$Cu(OH{)}_2+4N{H}_{4}OH\to [Cu\left(N{H}_3{)}_4\right](OH{)}_2+4H_{2}O$