Low concentration of oxygen in the blood and tissues of people living at high altitude is due to:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Low atmospheric pressure.
By Henry’s law, the amount of a gas that dissolves in a liquid is proportional to the partial pressure of the gas above it: \( p = K_{H}\,x \). At high altitudes the atmospheric pressure, and with it the partial pressure of oxygen, is lower than at ground level. Less oxygen therefore dissolves in the blood, giving low oxygen concentrations in the blood and tissues.
Why the other options are incorrect
Option (1) Low temperature. — Incorrect. Gases dissolve more, not less, at lower temperatures, so cold cannot explain a low oxygen concentration.
Option (3) High atmospheric pressure — Incorrect. Pressure falls with height, and a higher partial pressure would raise the amount of oxygen dissolved.
Option (4) Both low temperature and high atmospheric pressure — Incorrect. The pressure at high altitude is low, not high; and a high pressure would increase, not decrease, the dissolved oxygen.
NCERT (2026-27 edition):
Solubility of a Gas in a Liquid – …
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | 13-05 S1 | – | 14-06 S1 | – |