Is magnesium sulfate solid liquid gas or aqueous?

At ambient conditions (the temperatures and pressure in an ordinary lab room) magnesium sulfate will be solid. It will also dissolve easily in water to become aqueous; magnesium sulfate is the chemical formula for Epsom Salts. It will hydrate easily in the presence of humid air - but remain solid. You really won't get it to melt - it decomposes before melting - so you wouldn't get it as a liquid, nor would you get it to boil to become a gas. Like any solid, it will sublime just a little bit at low pressures but the vapor pressure of the salt is so low that for all practical purposes we wouldn't worry about it ever evaporating/subliming any more than we worry about table salt evaporating.