Question

Which one of the following compounds is not covalent?

Answer 1

Answer:

KCl

Explanation:

Hello,

Potassium chloride is well-known as an ionic compound owing to the shown-below greater-than-1.7 difference between the electronegativities of potassium and chlorine:

$\Delta E=E_{Cl}-E_K=3.16-0.82\\\Delta E=2.34$

This is by cause of the fact that such compounds that have a difference in the constituent elements' electronegativities greater than 1.7 are considered as ionic.

Best regards.

Answer 2

KCI is not a covalent compound, it is an ionic compound. 
A covalent compound is one in which each of the atoms involved contribute a specific number of electrons for sharing in order to from stable compound while an ionic compound is a compound formed when one atom donates electron to the other atom in the compound, in order to attain stability.  The compounds given in options A, B and D shared electrons while in KCl, potassium donates an electron to chlorine.