$\mathrm{Cu}^{2+}$ salt reacts with potassium iodide to give :

(B) $\mathrm{Cu}_{2} \mathrm{I}_{2}$

(A) $\mathrm{Cu}_{2} \mathrm{I}_{3}$

(C) $\mathrm{Cu}\left(\mathrm{I}_{3}\right)_{2}$

JEE Main · 2021 · 20 Jul 2021 · Shift 2 · d and f Block Elements

Cu^{2 +}

salt reacts with potassium iodide to give :

(A) $Cu_{2} I_{3}$
(B) $Cu_{2} I_{2}$ ✓ Correct
(C) $Cu (I_{3})_{2}$
(D)CuI

Answer: (B)

Solution

Iodide reduces copper(II) to copper(I) and is itself oxidised to iodine, and the copper(I) is removed from solution at once as its sparingly soluble iodide:

2 C u^{2 +} + 4 I^{-} \to C u_{2} I_{2} + I_{2}

The very low solubility of cuprous iodide is what drives the redox step, since it keeps the copper(I) concentration too small for disproportionation. The white precipitate formed is cuprous iodide,

C u_{2} I_{2}

JEE Main · 2021 · 20 Jul 2021 · Shift 2 · Single correct option

Practise more: all JEE Main PYQs on d and f Block Elements →

More JEE Main questions on d and f Block Elements

$MnO_{4}^{2 -}$ , in acidic medium, disproportionates to :
JEE Main 2026View solution →
Consider the following reactions:
$NaCl + K_{2} Cr_{2} O_{7} + H_{2} SO_{4} \to A + KHSO_{4} + NaHSO_{4} + H_{2} O$ …
JEE Main 2026View solution →
Given below are some of the statements about Mn and $Mn_{2} O_{7}$ . Identify the correct statements
A. Mn forms the oxide $Mn_{2} O_{7}$ in which Mn is in its highest oxidation state.
B. Oxygen stabilizes the Mn in higher oxidation states by fo …
JEE Main 2026View solution →
On heating a mixture of common salt and $K_{2} Cr_{2} O_{7}$ in equal amount along with concentrated $H_{2} SO_{4}$ in a test tube, a gas is evolved. Formula of the gas evolved and oxidation state of the central metal atom in the gas r …
JEE Main 2026View solution →
Among the following oxides of 3d elements, the number of mixed oxides are _____. …
JEE Main 2026View solution →
The oxidation state of chromium in the final product formed in the reaction between KI and acidified $K_{2} Cr_{2} O_{7}$ solution is:
JEE Main 2026View solution →