Because they are not very reactive. As with most chemical bonds, energy is required to create a bond between Hydrogen and Oxygen to form water. Normally there is not enough energy being applied to the different component elements in the air to form water.
Nothing.
Nothing. Popping is a physical change.
Nothing will happen as neon is chemically inert.
Nothing "happens".
Nothing.
Nothing will happen. Helium is completely nonreactive.
Nothing, i could just imagine the iron fillings would sink to the bottom and over time rust.
nothing
Nothing will happen as neon is chemically inert due to the presence of completely filled orbitals.
Nothing happens. A scratch is nothing to worry about. If the skin is broken, wash it with soap and water. You can apply an antibiotic if you want to. Such as Ozonol or some Hydrogen Peroxide.
nothing
There are a few similarities (they're both diatomic gases at room temperature, for example). Chemically, though, they're really nothing alike at all.