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CMC Medical CMC-Medical VELLORE Solved Paper-2015

  • question_answer
    In the past the age of the fossils was generally determined by radiocarbon method and other methods involve radioactive elements found in the rocks. More precise methods, which were used recently and led to the revision of the evolutionary periods for different groups of organisms, includes

    A)  study of carbohydrates / proteins in families

    B)  study of the conditions of fossilization

    C)  Electron Spin Resonance (ESR) and from/DNA

    D)  study of carbohydrates / proteins in rocks

    E)  None of the above

    Correct Answer: C

    Solution :

                    Electron spin resenance measures the number of charges occupying deep traps in the crystals band-gap. By measuring ^he change in absorption of microwave energy within a continuously varying strong magnetic field, this method detects the number of unpaired spins of electronic charge, trapped at various defects in the mineral lattice. The basic principles of ESR are the same as those described for luminescence, i.e. electron becomes trapped and stored as a result of ionising radiation, e.g. of ESR dating are dating of coral reefs (e.g. pleistocene raised coral reefs of burbados) and dating of tooth enamel.


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