the atomic number of four elements p, q,r, s are 6,8,10 and 12 respectively. the two elements which can bond ionically are:

The atomic numbers of four elements A, B, C, and D are 6,8,10, and 12 respectively. The two elements which can react to form ionic bonds (or ionic compounds) are B (8= 2,6) and D (12 =2,8,2). So D donates its two electrons to B to fulfill their octet.

Explanation:

it is the most commonly accepted one