Which one of the following gases dissolves in water to give acidic solution?

Carbon dioxide (CO2) is the gas that dissolves in water to produce an acidic solution. When CO2 dissolves, it reacts with water molecules to form carbonic acid (H2CO3) [2]. This weak acid subsequently dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-) [3]. The release of these hydrogen ions increases the acidity of the solution and lowers its pH level [1]. This chemical process is the fundamental driver of ocean acidification, where the absorption of atmospheric CO2 leads to a more acidic marine environment [3]. In contrast, gases like oxygen and nitrogen dissolve in water but do not react chemically to form acidic species, thus remaining relatively neutral in their effect on pH. Hydrogen gas also does not form an acidic solution upon dissolution in water under standard conditions.

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 18: Ocean Acidification > How it reacts? > p. 264
2. [2] https://www.epa.gov/ocean-acidification/understanding-science-ocean-and-coastal-acidification
3. [3] https://www.nature.com/scitable/knowledge/library/ocean-acidification-25822734/