Question

Which of the following are phase changes? (Select all that apply.)

sublimation

reactions

melting

gases

Answer 1

The phase changes among the options you provided are:

1. **Sublimation** - This is a phase change where a substance transitions from a solid to a gas without passing through the liquid phase.
2. **Melting** - This is a phase change where a substance transitions from a solid to a liquid.

The other options, "reactions" and "gases," do not represent phase changes. "Reactions" typically refer to chemical reactions while "gases" is a state of matter rather than a phase change.

So, the correct selections are **sublimation** and **melting**.