If $\mathrm{H}_{2} \mathrm{S}$ gas is passed into a solution of $\mathrm{Cu}^{2+}, \mathrm{Cd}^{2+}$ having…

If $\mathrm{H}_{2} \mathrm{S}$ gas is passed into a solution of $\mathrm{Cu}^{2+}, \mathrm{Cd}^{2+}$ having excess of $\mathrm{KCN}$.
  1. $\mathrm{CuS}$ and $\mathrm{CdS}$ both are precipitated.
  2. soluble complex $\left[\mathrm{Cu}(\mathrm{CN})_{4}ight]^{3-}$ and $\quad\left[\mathrm{Cd}(\mathrm{CN})_{4}ight]^{2-}$ are formed and no effect of passing $\mathrm{H}_{2} \mathrm{S}$ gas
  3. soluble complex $\left[\mathrm{Cu}(\mathrm{CN})_{4}ight]^{3-}$ and $\left[\mathrm{Cd}(\mathrm{CN})_{4}ight]^{2-}$ are formed, of which $\mathrm{CdS}$ is precipitated as yellow ppt.
  4. soluble complex $\left[\mathrm{Cu}(\mathrm{CN})_{4}ight]^{3-}$ and $\left[\mathrm{Cd}(\mathrm{CN})_{4}ight]^{2-}$ are formed of which $\mathrm{CuS}$ is precipitated as black ppt.

Solution

soluble complex $\left[\mathrm{Cu}(\mathrm{CN})_{4}ight]^{3-}$ and $\left[\mathrm{Cd}(\mathrm{CN})_{4}ight]^{2-}$ are formed, of which $\mathrm{CdS}$ is precipitated as yellow ppt.

Asked in: JEE-TOPICTESTS-CHEMISTRY

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