Element M is a shiny and highly reactive metal (melting point 63°C), and element X is a highly reactive nonmetal (melting point - 7.2°C). They react to form a compound with the empirical formula MX, a colorless, brittle white solid that melts at 734°C. When dissolved in water or when in the molten state, the substance conducts electricity. When chlorine gas is bubbled through an aqueous solution containing MX, a reddish-brown liquid appears and Cl- ions are formed. From these observations, identify M and X. (You may need to consult a handbook of chemistry for the melting-point values.)