International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

What is a key reason for the use of carbon dioxide in fizzy drinks?

1. It is a flavoring agent

2. It is soluble in water

3. It increases the shelf life

4. It acts as a preservative

The correct answer is: It is soluble in water

The use of carbon dioxide in fizzy drinks is primarily due to its solubility in water. When carbon dioxide is dissolved in water under pressure, it forms carbonic acid, which contributes to the drink's characteristic fizz and effervescence. This not only enhances the sensory experience by providing a refreshing, bubbly texture but also contributes to the overall taste profile of the beverage. The dissolved gas can create a pleasant tingling sensation when consumed, making the drink more enjoyable. Other options relate to different functions that may be associated with food and beverage preservation or enhancement, but they do not accurately describe the primary function of carbon dioxide in carbonated drinks. While carbon dioxide can have some effect on the shelf life of products and act as a mild preservative, its main role in fizzy drinks is linked to its ability to dissolve in water, creating carbonation.