The correct statement(s) is/are:
a. Thermal stability of alkaline earth metal chloride decreases with increasing molecular mass but reverse order is true for their melting point
b. Thermal stability of boron halides increases with decreasing molecular mass but reverse order is true for their melting point
c. Thermal stability of beryllium halides increases with decreasing molecular mass and same order is also true for their melting point
d. Thermal stability of hydra acids of halogens increases with decreasing molecular mass but reverse order is true for their melting point.