JEE Main & Advanced Sample Paper JEE Main Sample Paper-19

  • question_answer 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

    Correct Answer: B

    Solution :

     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. \[{{H}_{2}}S{{O}_{4}}.\] \[2BaC{{l}_{2}}+{{K}_{2}}C{{r}_{2}}{{O}_{7}}+3{{H}_{2}}S{{O}_{4}}\] \[\xrightarrow{{}}{{K}_{2}}S{{O}_{4}}+2BaS{{O}_{4}}+\underset{\begin{smallmatrix}  Chromyl\,chloride \\  (red\,\,gas) \end{smallmatrix}}{\mathop{2Cr{{O}_{2}}C{{l}_{2}}}}\,+3{{H}_{2}}O\]


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