Consider the heating curve for water. Temperature (°C)
Heating Curve for Water
160
140
120
100
80
60
40
20
0
-20
1 2 3 4 5 6 7 8 9 10
Time (min)
At what temperature does the solid start melting?
O-20°C .

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.

catya your not at all which answer i've seen you do this on another question!

the answer is c.the valence of the atoms combine .