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

  • question_answer
    Specific volume of cylindrical virus particle is \[6.02\times {{10}^{-2}}\,cc/g\] whose radius and length are \[7\,\overset{o}{\mathop{A}}\,\] and \[10\,\overset{o}{\mathop{A}}\,\] respectively. If \[{{N}_{A}}=\,\,6.02\times {{10}^{23}}\] find molecular weight of virus:                                                                     [AIPMT 2001]

    A)  15.4 kg/mol      

    B)  \[1.54\times {{10}^{4}}kg/mol\]

    C)  \[3.08\times {{10}^{4}}kg/mol\]          

    D)  \[3.08\times {{10}^{3}}kg/mol\]

    Correct Answer: A

    Solution :

    Specific volume (volume of 1 g) cylindrical virus particle \[=6.02\times {{10}^{-2}}\,cc/g\]
    Radius of virus \[(r)=7\times {{10}^{-8}}\,cm\]
    Length of virus \[=10\times {{10}^{-8}}\,cm\]
    Volume of virus
    \[=\pi {{r}^{2}}\ell =\frac{22}{7}\times {{(7\times {{10}^{-8}})}^{2}}\times 10\times {{10}^{-8}}\]
    \[=154\times {{10}^{-23}}cc\]
    Weight of one virus particle
    \[\text{=}\frac{\text{volume}}{\text{specific}\,\text{volume}}\text{=}\frac{154\times {{10}^{-23}}}{6.02\times {{10}^{-2}}}\]
                \[\therefore \]      Mol. wt. of virus = Wt. of \[{{N}_{A}}\] particle
    \[=\frac{154\times {{10}^{-23}}}{6.02\times {{10}^{-2}}}\times 6.02\times {{10}^{23}}\]
    \[=15400\,g/mol=15.4\,kg/mol\]


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