The following would represent enthalpy (a change in potential energy)
a) When the surrounding air gets colder
b) When water temperature increases in a calorimeter
c) When an ice cube melts
d) When a beaker is heated with a Bunsen burner
This question has been very confusing. I believe the answer may be C since an ice cube melting is a spacial change which may be a change in potential energy. And the others represent temperature changes. But an ice cube melting could also represent a temperature change, so im not sure.