Which of the alkaline earth metal halides given below is essentially covalent in nature?

BeCl2 is covalent in nature due to the small size and high charge of the Be²⁺ cation, which results in high polarization power. The small size of Be²⁺ allows it to polarize the electron cloud of the Cl⁻ anion significantly, leading to a substantial covalent character in the Be-Cl bond. In contrast, the larger alkaline earth metal cations (Mg²⁺, Ca²⁺, Sr²⁺) have lower polarizing power and form more ionic compounds.