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:
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.
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.
True, because if it wasn't a chemical reaction it would have proceeded to stay the same. but it begins to bubble. sorry if this isn't the best answer I'm trying my best.