Concept:The fizzy, refreshing taste of carbonated drinks is caused by dissolved carbon dioxide gas.
Explanation:Fizzy drinks are made by dissolving carbon dioxide under high pressure into the liquid.
While the bottle is sealed, the pressure keeps the gas dissolved in the solution.
When the bottle is opened, the pressure drops suddenly, so the dissolved gas escapes as tiny bubbles and creates the familiar fizz.
In water, this dissolved
CO2 forms a weak acid called carbonic acid, which gives the drink its sharp, pleasant, refreshing taste.
The other substances in the options play different roles: glucose adds sweetness, hydrogen is not present in the free state, and sodium citrate is used mainly as a flavouring or preservative.
Therefore, the characteristic refreshing taste is due to the presence of carbon(IV) oxide.
Answer:A. Carbon(IV)oxide
(CO2)