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WORKSHEET-1(ATOMS) (RUTHERFORD’S ATOM MODEL, IMPACT PARAMETER, DISTANCE OF CLOSEST
               APPROACH))


         1          Which of the following quantities has the same dimensions as Planck’s constant?
                    (a)angular momentum      (b)torque      (c)energy           (d)pressure
         2          When  α-particles are sent through a thin gold foil, most of them go straight through the foil,
                    because
                    (a)alpha particles are positively charged
                    (b)mass of  α-particle is more than mass of electron
                    (c)most of the part of an atom is empty space
                    (d)alpha-particles move with high velocity
         3          The existence of positively charged nucleus was established by
                    (a)Bohr’s model of H-atom
                    (b)Positive ray analysis
                    (c) α scattering experiment
                    (d)Thomson’s model of atom
         4          The angle of scattering   for zero value of impact parameter b is_______________.
         5          Alpha ray____________________led to the discovery of_________________.
         6          The scattering angle will decrease with the______________in impact parameter.
         7          The K.E of α-particle incident on gold foil is doubled. How does the distance of closest approach
                    change?
         8          In a Geiger-Marsden experiment, calculate the distance of closest approach to the nucleus of
                    Z=80, when an α-particle of 8 MeV energy impinges on it before it comes momentarily to rest
                    and reverses its direction.
         9          In a head-on collision between an α-particle and gold nucleus (Z=79), the distance of closest
                    approach is 39.5 fermi. Calculate the energy of α-particle.
         10         (a)Define distance of closest approach and impact parameter.
                    (b)What are the limitations of Rutherford’s model of an atom?
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