Identify which 2 of the following processes involve an exothermic change: melting, boiling, freezing, deposition and sublimation
An exothermic reaction involves an output of heat, so heat is lost overall. This would mean that boiling and melting are definitely not exothermic as they involving putting in heat. Freezing is an exothermic reaction as it involves losing heat.Sublimation involves changing straight from a solid to a gas, whereas deposition involves changing rapidly from a gas to a solid. Therefore deposition is the other exothermic process, since this also involves losing heat.
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