What is the empirical formula of a compound that contains 30.4% nitrogen and 69.6% oxygen by mass?

How could a student test the effect of removing heat from a gas that is stored in a sealed container? what must occur in order for matter to change states?

Asolution is made by dissolving 2.3 moles of sodium chloride (nacl) in 0.155 kilograms of water. if the molal boiling point constant for water (kb) is 0.51 °c/m, what would be the boiling point of this solution? show all the steps taken to solve this problem.

Suppose you discovered a new element with 120 protons and 2 electrons in its outer level . i'm what group does this new element belong? what properties would you expect it to have