Chemical reaction has occurred when two compounds are mixed and light is emitted, the color changes, and heat is liberated.
Answer: Option A
Step-by-step explanation:
Chemical mixture is a combination of two or more elements or substances and since here light s also emitted, hence that cant be the answer. Chemical nucleus exchange and chemical compromise doesn't deal with the emission of light as they act as intermediate and transfer of nucleus takes place.
Chemical reaction is when two or more compounds mix and the output comes as a result of bombardment. Hence chemical reaction is the best option.