In the analysis of basic radicals,the group reagent $H_2S$ gas is generally used in which groups?

Which of the following statements is incorrect?

Three different samples of a salt solution give the following test results: One sample gives a white precipitate with ammonia solution. One sample gives a white precipitate with dilute $NaCl$ solution. One sample gives a black precipitate with $H_2S$. Identify the salt.

Lead sulfate is soluble in which of the following?

$A$ (Orange color compound) $\xrightarrow{(B) + \text{conc. } H_2SO_4}$ $C$ (Red gas) $\xrightarrow{NaOH + AgNO_3}$ $D$ (Red ppt.) $\xrightarrow{\text{NH}_3 \text{ solution}}$ Yellow solution.
$B$ $\xrightarrow[\Delta]{NaOH}$ $F \uparrow$ (Gives white fumes with $HCl$).
Identify $B$ and $F$ respectively :-

Which of the following is sparingly soluble in cold water and fairly soluble in hot water?