NEET Chemistry Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ NEET PYQ-Some Basic Concepts Chemistry

  • question_answer
    How many grams of concentrated nitric acid solution should be used to prepare 250 mL of \[\text{2}\text{.0}\,\text{M}\]\[HN{{O}_{3}}\]. The concentrated acid is 70% \[HN{{O}_{3}}\].      [NEET 2013]

    A)  45.0 g conc. \[HN{{O}_{3}}\]   

    B)  90.0 g conc. \[HN{{O}_{3}}\]

    C)  70.0 g cone. \[HN{{O}_{3}}\]

    D)  54.0 g conc. \[HN{{O}_{3}}\]

    Correct Answer: C

    Solution :

    Given, morality of solution = 2
    Volume of solution\[=250\,mL=\frac{250}{1000}=\frac{1}{4}L\]Molar mass of
                \[HN{{O}_{3}}=1+14+3\times 16=63\,g\,mo{{l}^{-1}}\]
    \[\because \]       Molarity
    \[=\frac{\text{weight}\,\text{of}\,\,HN{{O}_{3}}}{\text{mass}\,\text{of}\,HN{{O}_{3}}\times \text{volume}\,\text{of}\,\text{solution}\,(L)}\]
    \[\therefore \]Weight of \[HN{{O}_{3}}=\] morality \[\times \]mol. Mass
    \[=2\times 63\times \frac{1}{4}g=31.5g\]
    It is the weight of \[100%\,HN{{O}_{3}}\].
    But the given acid is\[70%\,\,HN{{O}_{3}}\].
    \[\therefore \]Its weight \[=31.5\times \frac{100}{70}g=45g\]


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