Every element in group one has electron in its outer shell. Every element in group two has electrons in its outer shell. need help

If 1.8 l of water is added to 2.5l of a 7.0 molarity koh solution, what is the molarity of the new solution

This image is an example of a(n) a) atom. b) compound. c) mixture. d) molecule.

Aroom with dimensions 7.00m×8.00m×2.50m is to be filled with pure oxygen at 22.0∘c and 1.00 atm. the molar mass of oxygen is 32.0 g/mol. how many moles noxygen of oxygen are required to fill the room? what is the mass moxygen of this oxygen?