$A$ metal nitrate reacts with $KI$ to give a black precipitate which on addition of excess of $KI$ converts into an orange-colored solution. The cation of the metal nitrate is

$A$ $0.3 \, M$ $HCl$ solution contains the following ions: $Hg^{2+}, Cd^{2+}, Sr^{2+}, Fe^{2+}, Cu^{2+}$. The addition of $H_2S$ to the above solution will precipitate which of the following?

Which reagent is used in the qualitative analysis of Group $IV$ cations?

Which reagents are used for the identification of Group $IV$ cations?

Salt $X$ is:
$X \text{ (Colourless salt)}$ $\xrightarrow[\Delta]{NaOH} Y$ $\xrightarrow{HCl} \text{White fumes}$
$X \text{ (Colourless salt)}$ $\xrightarrow{CaCl_2} Z \text{ (White ppts.)}$ $\xrightarrow{KMnO_4} \text{Colourless solution}$

Lead sulfate is soluble in which of the following?