Of the following sulphides,which one is insoluble in dilute acids but soluble in alkalies?

Among $Fe^{3+}$, $Pb^{2+}$, $Cu^{2+}$, and $Mn^{2+}$, identify the one that gets precipitated out while passing $H_2S$ gas in the presence of $NH_4OH$ as a group reagent. The highest possible oxidation state of the corresponding metal is:

Given below are certain cations. Using inorganic qualitative analysis,arrange them in increasing group number from $0$ to $VI$.
$A$. $Al^{3+}$ $B$. $Cu^{2+}$ $C$. $Ba^{2+}$ $D$. $Co^{2+}$ $E$. $Mg^{2+}$
Choose the correct answer from the options given below.

Nessler's reagent is used to detect

Consider the following sequence of reactions:
$M^{2+}(aq.)$ $\xrightarrow{NH_4Cl(s) + (NH_4)_2CO_3 \, sol.} Q \downarrow$ $\xrightarrow[\text{Followed by addition of } (NH_4)_2C_2O_4]{CH_3COOH} R \downarrow$
Which of the following cations can form precipitate $Q$ but does not form precipitate $R$?

Three separate samples of a solution of a single salt gave these test results: one formed a white precipitate with excess ammonia solution,one formed a white precipitate with dilute $NaCl$ solution,and one formed a black precipitate with $H_2S$. The salt could be: