The Atomic number for sodium is 11 cause it contains 11 protons. I hope this helps..
Yes, light enters your eye and makes things visible. It's only a small portion of the elctromagnetic spectrum. It's called "visible light." What other things does the question want to know? I could go in a describe what light really is but I think itd be unnecessary.
A thermometer should be air dried so as to not damage it or anything similar. The three steps to cleaning it are washing, rinsing, and air drying it after. You shouldn't try to dry it other ways because it can damage it and this can cause a lot of troubles, so things cold air blowers or similar things can be very good in cleaning your thermometer.