NEET Sample Paper NEET Sample Test Paper-4

  • question_answer
    What amount of lime, \[Ca{{(OH)}_{2}}\] required to remove 'the hardness of \[60\,L\] of pond water containing \[1.62\text{ }mg\] of calcium bicarbonate per \[100\text{ }mL\] of water?

    A)  \[0.576\text{ }g\]                   

    B)  \[0.642\text{ }g\]

    C)  \[0.444\text{ }g\]                   

    D)  \[0.342\text{ }g\]

    Correct Answer: C

    Solution :

    \[\underset{162\,g}{\mathop{Ca{{(HC{{O}_{3}})}_{2}}}}\,+\underset{74\,g}{\mathop{Ca{{(OH)}_{2}}}}\,\xrightarrow{O}2CaC{{O}_{3}}+2{{H}_{2}}O\] 100 mL of pond water has \[Ca{{(HC{{O}_{3}})}_{2}}\]             \[=1.62\,mg=1.62\times {{10}^{-3}}g\] \[60,000\,mL\] has             \[Ca{{(HC{{O}_{3}})}_{2}}=\frac{1.62\times {{10}^{-3}}}{100}\times 60000\] \[162\,g\]of  \[Ca{{(HC{{O}_{3}})}_{2}}\] requires                                     \[Ca{{(OH)}_{2}}=74\,g\] \[0.972\text{ }g\] of \[Ca{{(HC{{O}_{3}})}_{2}}\] requires \[Ca{{(OH)}_{2}}\]             \[=\frac{74}{162}\times 0.972=0.444g\]


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