The question requires us to analyze four events (production of a solid, formation of a gas, heat released and melting of a solid) and determine which of them does not represent an evidence to the ocurrence of a chemical reaction.
From the options given, we can affirm that the production of a solid and formation of a gas, considering that there are precursors reactants in the system, are clear evidence of a chemical reaction ocurring - produce (or release) a compound starting from other materials is a chemical reaction. With that, we can cross off these two options.
For the other events, we can say that heat realease from the interaction of two or more molecules or still, from the decomposition of one compound, is an evidence to the occurrence of a chemical reaction too.
Therefore, the remaining option is "melting of a solid" - this is a physical transformation, where a solid
W
