Aquatic species are more comfortable in cold water due to
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Higher solubility of gases at low temperature.
Aquatic animals breathe the oxygen dissolved in water. The solubility of a gas in a liquid depends on temperature:
Dissolving a gas is an exothermic process, so by Le Chatelier’s principle, solubility falls as the temperature rises.
Cold water therefore holds more dissolved oxygen than warm water. So aquatic species are more comfortable in cold water because of the higher solubility of gases at low temperature.
Why the other options are incorrect
Option (2) Increase in gas solubility at higher temperatures — Incorrect. This is the reverse of the truth; gases are less soluble in warm water.
Option (3) Decrease in vapour pressure at low temperature — Incorrect. The vapour pressure of water does not decide how much oxygen is dissolved in it.
Option (4) Higher density of water at lower temperature — Incorrect. Density does not control the oxygen supply, and water is densest at 4 °C, not at the lowest temperature.
NCERT (2026-27 edition):
Solubility of a Gas in a Liquid – …
| Gas | Temperature/K | KH/kbar |
|---|---|---|
| N2 | 293 | 76.48 |
| N2 | 303 | 88.84 |
| O2 | 293 | 34.86 |
| O2 | 303 | 46.82 |