Question

The atomic number and atomic weight of a radioactive element 84 and 210 respectively. After emitting an alpha-ray from it, their atomic weight and atomic number are:
(a) 201,84 (b) 206,82 (c)208,84 (d) 208,82

Please answer with explaination.​

Answer 1

The speed and hence the energy of an alpha particle ejected from a given nucleus is a specific property of the parent nucleus and determines the characteristic range or distance the alpha particle travels. Though ejected at speeds of about one-tenth that of light, alpha particles are not very penetrating. They have ranges in air of only a few centimetres (corresponding to an energy range of about 4 million to 10 million

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