BHU PMT BHU PMT (Mains) Solved Paper-2009

  • question_answer
    0.42 g magnesium carbonate and 0.5 g calcium carbonate are; heated strongly. What is the quantity left?

    A)  0.48 g                                  

    B)  0.80 g

    C)   0.42 g                                 

    D)  0.28 g

    Correct Answer: A

    Solution :

                     \[\underset{\begin{smallmatrix}  1\,mol \\  \frac{0.42}{84}=0.005 \end{smallmatrix}}{\mathop{MgC{{O}_{3}}}}\,\xrightarrow{\Delta }\underset{\begin{smallmatrix}  1\,mol \\  0.005\,mol \end{smallmatrix}}{\mathop{MgO}}\,+C{{O}_{2}}\] \[\underset{\begin{smallmatrix}  1\,mol \\  \frac{0.5}{100}=0.005 \end{smallmatrix}}{\mathop{CaC{{O}_{3}}}}\,\xrightarrow{\Delta }\underset{\begin{smallmatrix}  1\,mol \\  0.005\,mol \end{smallmatrix}}{\mathop{CaO}}\,+C{{O}_{2}}\] Total weight       \[=wt.\,of\,MgO+wt\,of\,CaO\] \[=0.005\times 40+0.005\times 56\] \[=0.48g\]


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