The emission of an `alpha or a beta` particle by a radioactive element forms a new element. However, successive emission of some `alpha or beta`- particles may give rise to an isotope or an isobar of the original element. In many cases, positron emission or `K -` electron capture takes place, leading again to the formuation of new elements, alongwith the emission of neutrinos or antineutrinos. These emission also change the neutron/proton `(n//p)` ratio so that they give rise to stable isotopes which lie in the stability belt. However, in any disintegration reaction, the law of conservation of atomic number and mass number is always obeyed and this helps us to calculate the number of `alpha and beta-` particles emitted in the reaction. The number of `alpha - and beta-` particle emitted in nuclear reaction `._(90)Th^(288) rarr ._(83)Bi^(212)` are respectivelyA. 4, 1B. 3, 7C. 8, 1D. 4, 7