All except mercury are solids at room temperature

That's not a question, but I guess I'll just vomit some information at you and hope I hit a target.

First of all, not true. Unless you're talking multiple choice kind of thing.

Room temperature is 20 degrees C / 68 degrees F / 293 degrees K

At this temperature, most elements are solids, but

Mercury and bromine are liquids

Hydrogen, helium, nitrogen, oxygen, flourine, neon, chlorine, argon, krypton, xenon, and radon are all gases.