High-mass radio-nuclides, which may be either alpha or beta emitters, belong to one of four decay chains, depending on whether their mass number A is of the form 4n,4n + 1, 4n + 2, or 4n + 3, where n ts a positive integer.

(a) Justify this statement and show that if a nuclide belongs to one of these families, all its decay products belong to the same family. Classify the following nuclides as to family: (b) 235U,

(c) 236U,

(d) 238U,

(e) 239Pu,

(f) 240Pu,

(g) 245Cm,

(h) 246Cm,

(i) 249Cf and

(j) 253Fm.