7th Class Science Physical and Chemical Changes Question Bank Physical and Chemical Changes

  • question_answer
    Observe the given reaction sequence carefully.
    Acetic acid + Sodium hydrogen carbonate \[\xrightarrow{{}}\](i)
    \[(i)+Ca{{(OH)}_{2}}\xrightarrow{\,}\,(ii)+Water\]
    What could (i) and (ii) be?

    A)
    (i) (ii)
    \[CaC{{O}_{3}}\] \[C{{O}_{2}}\]
                   

    B)
    (i) (ii)
    \[{{H}_{2}}O\] \[CaC{{O}_{3}}\]
                   

    C)
    (i) (ii)
     \[C{{O}_{2}}\] \[CaC{{O}_{3}}\]
                   

    D)
    (i) (ii)
    \[{{H}_{2}}O\] \[C{{O}_{2}}\]

    Correct Answer: C

    Solution :

    \[\underset{Acetic\,acid}{\mathop{C{{H}_{3}}COOH}}\,+\underset{\begin{smallmatrix}  Sodium\,\,hydrogen \\  carbonate \end{smallmatrix}}{\mathop{NaHC{{O}_{3}}}}\,\] \[\to \,\underset{Sodium\,\,acetate}{\mathop{C{{H}_{3}}COONa}}\,+\underset{(i)}{\mathop{C{{O}_{2}}}}\,\uparrow +\underset{Water}{\mathop{{{H}_{2}}O}}\,\] \[\underset{\begin{smallmatrix}  Carbon \\  dioxide  \\  (i) \end{smallmatrix}}{\mathop{C{{O}_{2}}}}\,+\underset{\begin{smallmatrix}  Calcium \\  hydroxide \end{smallmatrix}}{\mathop{Ca{{(OH)}_{2}}}}\,\to \underset{\begin{smallmatrix}  Calcium \\  carbonate  \\  (ii) \end{smallmatrix}}{\mathop{CaC{{O}_{3}}}}\,+\underset{Water}{\mathop{{{H}_{2}}O}}\,\]                


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