Match Column I with Column II. Column I: (a) after emission of one α-particle and one β−-particle; (b) after emission of two α-particles and one β−-particle; (c) after emission of one α-particle and two β−-particles; (d) after emission of two α-particles and two β−-particles. Column II: (p) atomic number will decrease by 3; (q) atomic number will decrease by 2; (r) mass number will decrease by 8; (s) mass number will decrease by 4.