BCECE Medical BCECE Medical Solved Papers-2010

  • question_answer
    Which is always present in photochemical smog?

    A)  \[{{O}_{3}}\]

    B)  \[C{{O}_{2}}\]

    C)  \[S{{O}_{2}}\]

    D)  \[C{{H}_{4}}\]

    Correct Answer: A

    Solution :

    Photochemical smog occurs at high temperature over cities and towns due to smoky air, emission of nitrogen oxides and hydrocarbons from automobile exhausts and solar energy. Nitrogen dioxide splits into nitric oxide and nascent oxygen. Nascent oxygen combines with molecular oxygen to form ozone. Ozone reacts with hydrocarbons to form aldehydes and ketones. Nitrogen oxide, oxygen and ketones combine to form Peroxy Acyl Nitrates (PAN), which is responsible for the eye irritation characteristic of photochemical, smog. This smog was first observed in Los Angeles, so called as Los Angeles smog. Classical (London) smog reported in 1952 in London. It occurs at low temperature, contains sulphur gases (hydrogen Sulphide, sulphur dioxide) smoke and dust particles.


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