Why the gas is dissolved when the cola is in the bottle?

Gas is dissolved in cola under high pressure within the bottle, which allows more carbon dioxide (CO2) to be held in solution. When the bottle is sealed, the pressure keeps the gas in a dissolved state. Once the bottle is opened, the pressure is released, causing the gas to escape and form bubbles, which creates the characteristic fizz. This process is a result of Henry's Law, which states that the amount of gas that can dissolve in a liquid is directly proportional to the pressure of the gas above the liquid.