You drip a liquid substance onto a metal plate. You hear a hiss, and see a gas rising from the spot where the liquid touches the metal plate. What indicates a chemical reaction in this scenario?

the formation of a new gas

the hissing sound as the liquid touches the metal

the decrease in temperature as the liquid touches the metal

the liquid being in contact with a metal

h let me think

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.