(i) A radioactive nucleus 'A' undergoes a series of decays as given below :
`A overset(alpha)rarr A_(1) overset(beta)(rarr)A_(2)overset(alpha)rarrA_(3)overset(gamma)(rarr)A_(4)`.
The mass number of atomic number of `A_(2)` are `176` and 171 respectively. Determine the mass and atomic numbers of `A_(4)` and A.
(ii) Write the basic nuclear processes underlying `beta` and `beta^(-)` decays.

Explanation

(i)
(ii) From the principle of conservation of energy and angular momentum `beta` particles spin is`1/2 (= h/(2pi))`, so the change must be the same order, however, it is found that spin is either unchanged or it faces an integral change. Neutrino Hypothesis successfully explains the phenomena. `beta^(-)` is used for an `e^(-)` and `beta^(+)` is used for `e^(+)`. An excited proton rich nucleus gets stability by capturing K-shell orbital `e^(-)`.
For `beta^(-)` decay, a neutron transforms into a proton within the nucleus as `n rarr e^(-) + bar(v) (+ve Q)` and for `beta^(+)` decay, a proton transform into a neutron within the nucleus as `p rarr n + e^(-) + v(-veQ)`.