The electronic configuration of four elements is:

(i) W: 2,6
(ii) X: 2,8
(iii) Y: 2,8,1
(iv) Z: 2,8,7

Which pair of atoms will form a covalent compound.

1. Two atoms of W
2. Two atoms of X
3. An atom of W & an atom of X
4. An atom of Y & an atom of Z

Two atoms of W

Reason — The electronic configuration of four elements :

(i) W: 2,6 — Atomic number 8
(ii) X: 2, 8 — Atomic number 10
(iii) Y: 2,8,1 — Atomic number 11
(iv) Z: 2,8,7 — Atomic number 17

Covalent bonding occurs between non-metals by sharing electrons. W needs 2 more electrons to complete its octet. So, two W atoms can share electrons with each other, forming a covalent bond
Hence, two atoms of W will form covalent bond.
However, X has completely filled outer shell, so it is not involved in covalent bond formation and bond between Y and Z is ionic.