A blue colouration is not obtained when

A blue colouration is not obtained when
  1. ammonium hydroxide dissolves in copper sulphate.
  2. copper sulphate solution reacts with
    $\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}ight]$
  3. ferric chloride reacts with sod. ferrocyanide.
  4. anhydrous $\mathrm{CuSO}_{4}$ is dissolved in water.

Solution

$2 \mathrm{CuSO}_{4}+\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}ight] \longrightarrow$
$\mathrm{Cu}_{2}\left[\mathrm{Fe}(\mathrm{CN})_{6}ight]+2 \mathrm{~K}_{2} \mathrm{SO}_{4}$
Chocolate ppt. *

Asked in: JEE-TOPICTESTS-CHEMISTRY

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