Which one of the following gases gives acidic solution on dissolving in water ?

Carbon dioxide (CO2) is the gas that produces an acidic solution when dissolved in water. When CO2 dissolves in water, it reacts to form carbonic acid (H2CO3). This carbonic acid then dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-). The release of these hydrogen ions increases the acidity of the solution and lowers its pH level. This chemical process is the fundamental cause of ocean acidification, where atmospheric CO2 is absorbed by seawater. In contrast, gases like nitrogen, oxygen, and hydrogen do not react with water to form acidic species under standard conditions; nitrogen and oxygen are the most abundant atmospheric gases but remain relatively inert in terms of water pH [4]. Therefore, carbon dioxide is the correct choice as it chemically transforms into a weak acid upon dissolution [1].

Sources

1. [2] https://www.nasa.gov/wp-content/uploads/2023/06/making-o2-and-co2.pdf
2. [4] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > 12.3.2 Carbon Dioxide > p. 255
3. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 18: Ocean Acidification > How it reacts? > p. 264