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JEE Main & Advanced Sample Paper JEE Main Sample Paper-46

  • question_answer
    Apatite is a mineral that is found in tooth enamel. When fluoride toothpastes are used, this mineral is converted to fluoroapatite, which is more resistant to tooth decay. The formula of apatite is \[C{{a}_{5}}{{(P{{O}_{4}})}_{x}}F\]. What is the value of \[x\] if the compound contains 18.45% by weight of phosphorus? (Atomic weight of \[P=31,\,\,Ca=40,\,\,F=19\] and\[O=16\])

    A)  2                                

    B)  4                 

    C)  5                                

    D)  3

    Correct Answer: D

    Solution :

     % of \[P=\frac{x\times 31}{5\times 40+31x+64x+19}\times 100=18.45\]\[\Rightarrow \]\[x=3\]


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