What is the state of matter of water?
The state of matter of water is liquid. It can be in a state of a solid or gas.
The reason for all three is because water can occur in all three of these different states as a cause of its surroundings.
For example, water in a state of solid is ice where water is frozen under cold temperatures (i.e. below room temperature of a liquid).
Water in a state of liquid is just water (in this state at room temperature, for example).
Water in a state of gas can be water vapour as it's the gaseous phase of the water. This can occur through evaporation by boiling the water.