JEE Main & Advanced Sample Paper JEE Main Sample Paper-5

  • question_answer
    In an iodometric estimation, following reactions occur. \[2C{{u}^{2}}+4{{I}^{-}}\xrightarrow[{}]{{}}C{{u}_{2}}{{I}_{2}}+{{I}_{2}}\] \[{{I}_{2}}+2N{{a}_{2}}{{S}_{2}}{{O}_{3}}\xrightarrow[{}]{{}}2NaI+N{{a}_{2}}{{S}_{4}}{{O}_{6}}\] 0.24 mole of \[CuS{{O}_{4}}\] was added to excess of KI solution and the liberated iodine required 240 mL of hypo. Then, find the molarity of hypo solution.                                

    A)  5.0                        

    B)  3.0                     

    C)  1.0                        

    D)  5.5  

    Correct Answer: C

    Solution :

    Moles of pure\[CuS{{O}_{4}}=0.24=\]moles of \[N{{a}_{2}}{{S}_{2}}{{O}_{3}}\]reacted with\[{{l}_{2}}\]. Moles of\[N{{a}_{2}}{{S}_{2}}{{O}_{3}}=240\times {{10}^{-3}}\times M\]\[=0.24\] So,                          \[M=1.0\]

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