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  5. Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ

JEE Main & Advanced Chemistry Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ Sample Paper Topic Test - Some Basic Concepts of Chemistry

  • question_answer
    When \[Fe{{S}_{2}}\] is burnt in air, it converts into \[F{{e}_{2}}{{O}_{3}}.\] The change in percentage by weight of iron in the process is (Fe = 56)

    A) 23% increase

    B) 12% decrease

    C) 12% increase

    D) no change

    Correct Answer: A

    Solution :

    [a] \[\underset{Fe%\frac{56}{120}\times 100=46.67}{\mathop{\underset{56+32\times 2=120}{\mathop{Fe{{S}_{2}}}}\,}}\,\xrightarrow[{}]{{}}\underset{\frac{112}{160}\times 100\,=\,70}{\mathop{\underset{56\times 2+3\times 16\,=160}{\mathop{F{{e}_{2}}{{O}_{3}}}}\,}}\,\] Percent increase = 70 – 46.67 = 23% (approx.)


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