(a) 235 92X when α β particle is emitter mass number does not change but atomic number increases by 1 (isobar)
∴ When 2 successive β particles decay mass number does not change (isobar) but atomic number increases by 2.
Then α-particle decays, mass number decreases by 4 and atomic number decreases by 2.
Ultimately when 2 β particles decays and la-particle decays
This means to change 235 92X to 235 92X1 here, atomic number remains same but mass number decreases by 4
∴ In 6 steps [X → X1 → X2 → X3 →X4 →X5 →X5]
Atomic number remains same but mass number decreases by
6 x 4 = 24
(b) After every β decay isobar is formed and after α-decay isotope is formed
∴ Total 12 isobars and 6 isotopes are formed.