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).
When a substance changes from one state, or phase, of matter to another we say that it has undergone a change of state, or we say that it has undergone a change of phase. For example, ice melts and becomes water; water evaporates and becomes water vapor. These changes of phase always occur with a change of heat. Heat, which is energy, either comes into the material during a change of phase or heat comes out of the material during this change. However, although the heat content of the material changes, the temperature does not.