Option A: Carbonates of alkaline earth metals are insoluble in water. True. Alkaline earth metal carbonates (e.g., CaCO3,SrCO3,BaCO3 ) are generally insoluble in water, except BeCO3 and MgCO3, which are slightly soluble. Option B: Beryllium halides are covalent in nature. True. Beryllium has a small size and high charge density, which leads to high polarization of the halide ion ⟶ results in covalent bonding (as per Fajan's rules). Option C: The superoxides of alkali metals are colourless. False. Superoxides (e.g., KO2,RbO2,CsO2 ) are colored - typically yellow to orange - because of the presence of the paramagnetic O2‌−ion. Hence, this statement is not correct. Option D: Alkali metal halides have high negative enthalpies of formation. True. They are highly stable ionic compounds formed with large lattice energies and thus have large negative enthalpies of formation. Correct answer: Option C The superoxides of alkali metals are colourless. (Incorrect statement)