When sugar is heated it melts and then caramelize giving of water. After this, it turns blank (carbon) and then coverts to co2 (carbon dioxide) . So, heating of sugar is an endothermic , decomposition and oxidation reaction. When Ammonium Chloride is heated , it directly goes from solid state to vapour state without changing into liquid state. So, heating of Ammonium Chloride is an example of sublimation reaction.
