Which plate, oceanic or continental, must be more dense? How do you know
this?

Oceanic crust is not only thinner and denser than continental crust, and it is also much younger than it and has a different chemical composition. When magma from the mantle of the earth finds a way up, it comes into contact with water that cools it down quickly

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.