HPSC Assistant Professor Exam 2018
The concentration of dissolved oxygen (DO) in cold water can go up to
- (A) 8 ppm
- (B) 10 ppm
- (C) 14 ppm
- (D) 16 ppm
Answer: (B) 10 ppm
Explanation: Dissolved Oxygen (DO) levels are governed by Henry's law, which states that gas solubility decreases as temperature increases.
The concentration of dissolved oxygen (DO) in cold water can reach up to ~14.6 ppm, but in natural healthy environments, it is typically cited around 10 ppm, significantly higher than in warmer water (around 5 ppm at room temperature) because colder water holds more gas. This high DO level is crucial for cold-water fish like trout, with healthy levels often above 6.5-8 mg/L (ppm), while levels below 3-4 mg/L can be lethal.