$A$ laboratory reagent imparts green colour to the flame. On heating with solid $K_2Cr_2O_7$ and conc. $H_2SO_4$,it evolves a red gas. Identify the reagent.

Which of the following is an incorrect match for the precipitate (ppt) and its color?

To an aqueous solution containing ions such as $Al^{3+}, Zn^{2+}, Ca^{2+}, Fe^{3+}, Ni^{2+}, Ba^{2+}$ and $Cu^{2+}$,concentrated $HCl$ was added,followed by $H_{2}S$. The total number of cations precipitated during this reaction is/are:

Addition of $SnCl_2$ to $HgCl_2$ gives a precipitate of which color?

$A$ light greenish coloured salt was soluble in water. On passing $H_2S$ into the solution,a black precipitate was obtained which dissolved readily in $HCl$. The metal ion present is:

Consider the following reaction scheme: $D(\text{White ppt}) \xleftarrow{Na_2CO_3} A \xrightarrow[\text{in acetic acid}]{K_2CrO_4} B(\text{Yellow ppt})$ and $A \xrightarrow{dil.\ H_2SO_4} C(\text{White ppt})$. If $A$ is a metallic salt,then the white precipitate $D$ must be: