Question

The only item that exists on the planet in all three states of matter at standard pressure is what

Answer 1

water is the only one because it exists as ice, water, and water vapor

Answer 2

Water

Step-by-step explanation:

If we consider the planet to be Earth, it is water. It is the only item that exists in all three states of matter: Water (Liquid state), Ice (Solid state) and water vapor (Gaseous state) at standard pressure. No other elements/compound can exist in all three states at standard pressure. In fact, Earth is the only known planet to have this condition which makes it suitable for life.