[" brackets "],[L(1s^(2),2s^(2)p^(4))Q(1s^(2),2s^(2)2p^(6),3s^(2)3p^(5))],[P(1s^(2),2s^(2)2p^(6),3s^(2))R(1s^(2),2s^(2)2p^(6),3s^(2))],[" The formulae of fonic compounds that "],[" can be formed between these elements "],[" (a) "L_(2)P,RL,PQ" and "R_(2)Q(b)],[LP,RL,PQ" and "RQ],[" (c) "P_(2)L,RL,PQ" and "RQ_(2)(d)],[" LP,"R_(2)L,P_(2)Q" and "RQ,L(" Is "^(2),2s)]