How do the physical properties of nonmetals differ from the physical properties of metals?

Answer 1

Here is a good site that will give you all of the information you seek. Study it carefully.

http://chemed.chem.purdue.edu/demos/main_pages/2.2.html

Answer 2

Which group of elements are all gases at room temperature?

Answer 3

Look at group 18 or the periodic table.
http://www.webelements.com/