Later I heard that the price of an eye exam at target optical may vary from $29 to $229. So I think this may be the reason that why I can't find the price on the internet. if you want to have an eye exam at target optical, I strongly suggest you to make a call to know the exact price for en eye exam in that store.
Water does not commonly form a gas, but rather a vapor which is slightly different (but really just the name of a gas that is normally a liquid). - There is latent heat in water so you can remove energy without changing the temperature of the water (only exactly at a phase change though).
The water's temperature continues to rise as the energy is added until the temperature is 100 C. At that point, you continue to add energy but the temperature no longer rises. Instead, the water boils. The energy input now is going into moving water molecules from the liquid to the gas phase. The water molecules have attractive forces between them which constitute a low energy. You have to do work (add energy) on the molecules to pull them apart and make them a gas. The opposite occurs in solidification of water.