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).
Changing the amount of heat energy usually causes a temperature change. However, DURING the phase change, the temperature stays the same even though the heat energy changes. This energy is going into changing the phase and not into raising the temperature. That's why water doesn't get hotter while it boils. The temperature remains constant until the phase change is complete.