The ionic radius of metal M decreases as the charge on the metal M increases. The ionic radius is generally defined as the distance between the nucleus and the outermost electron of the ion. Hence, ionic radius becomes much lesser as the magnitude of the positive charge increases.
It is obvious from the various formulae of metal chlorides in the question that the metal forms cations M^2+, M^3+ and M^4+ respectively. The order of decreasing ionic radius of the compounds is;
The SI (international system) unit for molality is mol / kg, or solute moles per kg of peptides. A solution with a molality of 1 mol / kg is often described as "1 molal" or "1 m".
