A process or reaction in which heat is absorbed from the surroundings is called:

1. Classification depends on whether heat is taken in or given out. 2. When heat is absorbed from outside, the process or reaction is endothermic, e.g. dissolution of KNO$_3$ in water. 3. Heat being given out defines an exothermic change, the opposite. 4. Electrolytic and catalytic refer to electricity and catalysts, not to heat exchange, so they are wrong. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 3 "Chemical Reactions and Equations", p.48_