Question

Which of the following gives a coloured precipitate with $NaOH$ solution?

• A. $B{a}^{2+}$
• B. $M{g}^{2+}$
• C. $C{u}^{2+}$
• D. $N{H}_4^{+}$

Answer 1

The correct option is C $C{u}^{2+}$

$C{u}^{2+}$ ions react with sodium hydroxide to form a blue precipitate of cupric hydroxide.
$C{u}^{2+}+2NaOH\to Cu(OH{)}_2\downarrow +2N{a}^{+}$
$B{a}^{2+}$, $M{g}^{2+}$ and $N{H}_4^{+}$ ions react with sodium hydroxide solution to form white precipitates of barium hydroxide, magnesium hydroxide, and ammonium hydroxide, respectively.