AIIMS CRE, SNO-2024: Which gas is commonly present in soft drinks?

AIIMS CRE, SNO-2024

Applied Nutrition & Dietetics

Easy

Appeared in: AIIMS CRE, SNO-2024

Explanation

Carbon dioxide (CO2) is the gas dissolved under high pressure to create carbonated soft drinks, a process known as carbonation.
When dissolved in water, CO2 forms carbonic acid, which provides a characteristic tangy taste and also acts as a preservative, inhibiting microbial growth.
The fizziness or effervescence of soft drinks is caused by the dissolved CO2 gas escaping as bubbles when the pressure is released upon opening the container.
This application is based on Henry's Law, which states that the solubility of a gas in a liquid is directly proportional to the pressure of the gas over the liquid.

Option A: Oxygen is a highly reactive gas that promotes oxidation. Using it in soft drinks would lead to spoilage, altering the flavor and degrading the quality of the ingredients.
Option B: Nitrogen is much less soluble in water than CO2 and produces a different effect. It creates a creamy texture with very fine, stable bubbles, not the sharp fizziness typical of soft drinks.
Option D: Helium is an inert gas that is extremely insoluble in water. It cannot be dissolved in a liquid to create carbonation and would escape immediately.

Visual 1: Diagram: An illustration of Henry's Law, showing a container with liquid under two different pressures. The container with higher pressure has more gas molecules dissolved in the liquid, demonstrating the principle of carbonation.
Visual 2: Infographic: A comparative chart of Carbon Dioxide, Oxygen, Nitrogen, and Helium, detailing their properties (solubility, reactivity) and primary commercial uses to highlight why CO2 is uniquely suited for soft drinks.

Clinical Relevance

Nursing practice connection: Knowing Properties of Gases and Carbonation in Beverages helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding basic chemistry, such as gas solubility (Henry's Law), is a foundational concept in many scientific fields, including food science, pharmacology, and respiratory therapy.
In a clinical setting, the properties of gases are critical. For example, oxygen is administered for hypoxemia, and mixtures like Heliox (Helium-Oxygen) are used to reduce the work of breathing in patients with airway obstruction due to helium's low density.
While carbonated drinks are generally safe, excessive consumption can contribute to dental erosion (due to carbonic and other acids) and high sugar intake, which are relevant points for patient education on diet.

How to Approach the Question

First, identify the key terms in the question: 'gas' and 'soft drinks'. The question asks for the specific gas that gives soft drinks their characteristic property.
Think about the common term for fizzy drinks: 'carbonated beverages'. This term itself is a major clue, pointing directly to 'carbon'.
Evaluate the options based on general scientific knowledge. Carbon dioxide (CO2) is widely known to be used for carbonation.
Consider the properties of the other gases to confirm they are incorrect. Oxygen is reactive (causes rust/spoilage), Nitrogen is less soluble and used for a different texture (creamy), and Helium is very light and insoluble (used for balloons).
Based on the direct link between 'carbonated' and 'carbon dioxide', and the unsuitability of the other options, select CO2 as the correct answer.

Concept Tested & Keywords

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E6 textbook of Applied Biochemistry and Nutrition & Dietetics 2nd Edition Harbans Lal (pp 26-464 of 479) p. 464-469