Question

what happens to salt particles left over that cannot be dissolved in a solution? they are crystals. they change color. they spill out of the container. they release energy as heat.

Explanation:

When salt cannot dissolve in a solution, it forms its solid - state structure which is a crystal lattice. There is no color - change, spilling, or heat - release due to just being undissolved.

Answer:

They are crystals.