Question

what is happening to the particles in the substance between points d and e? freezing melting sublimating vaporizing

Explanation:

In a heating curve (the graph shown), the horizontal segments represent phase changes. Between D and E, the substance is undergoing vaporization (liquid to gas) as heat is added but temperature remains constant (latent heat of vaporization is absorbed, particles gain energy to overcome intermolecular forces and transition to gaseous state). Freezing is liquid to solid, melting is solid to liquid, and sublimating is solid to gas—none match D - E (which is liquid - gas transition).

Answer:

Vaporizing