• # question_answer 23) A laboratory reagent imparts green colour to the flame. heating with solid ${{K}_{2}}C{{r}_{2}}{{O}_{7}}$ and cone. ${{H}_{2}}S{{O}_{4}}$ it evolves a red gas. Identify the reagent A)  $CaC{{l}_{2}}$                            B)  $BaC{{l}_{2}}$C)  $CuC{{l}_{2}}$                               D)  None of these

The reagent is $BaC{{l}_{2}}$ which imparts green colour to flame. $BaC{{l}_{2}}$ forms chromyl chloride (which is red in colour), when treated with ${{K}_{2}}C{{r}_{2}}{{O}_{7}}$ and cone. ${{H}_{2}}S{{O}_{4}}.$ $2BaC{{l}_{2}}+{{K}_{2}}C{{r}_{2}}{{O}_{7}}+3{{H}_{2}}S{{O}_{4}}$ $\xrightarrow{{}}{{K}_{2}}S{{O}_{4}}+2BaS{{O}_{4}}+\underset{\begin{smallmatrix} Chromyl\,chloride \\ (red\,\,gas) \end{smallmatrix}}{\mathop{2Cr{{O}_{2}}C{{l}_{2}}}}\,+3{{H}_{2}}O$