Explain why you usually can't use just a single spectrum line to confirm the identity of an element

What does a particular point on a line of a phase diagram represent? o a. the maximum temperature a substance can exist at without bonds breaking b. the pressure created by the kinetic energy of molecules at a particular temperature c. the melting point or boiling point of a substance at a specific pressure d. the conditions in which temperature and pressure have equal effects on a substance

How are isotopes of the same chemical element alike? how are they different?

Is powdered sports drink ionic or covalent ? 10pts !