Question

In general, amount of dissolved Oxygen in water in a lake can vary on day and night basis, as well as on seasonal basis (summer and winter). Solubility of gas is governed by Henry's law and is inversely proportional to temperature of water. Which of the following is most appropriate?

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Higher water temperature $\Rightarrow$ lower dissolved oxygen (Henry's law: gas solubility inversely proportional to temperature).

Answer 1

The Correct Option is A

Step 1: Concept
Henry's Law and solubility of gases in liquids.

Step 2: Meaning
Henry's law states that the amount of gas dissolved in a liquid is directly proportional to the partial pressure of the gas and inversely proportional to the temperature.

Step 3: Analysis
Statement (A) correctly identifies that dissolved oxygen varies seasonally and diurnally. Statement (R) correctly explains this using Henry's law: higher temperatures (summer/daytime) reduce oxygen solubility, while lower temperatures (winter/night) increase it. (R) thus explains (A).

Step 4: Conclusion
Both (A) and (R) are correct, and (R) is the correct explanation of (A). Final Answer: (A)