Question

Assertion: Most fish when out of the water, die of suffocation.

Reason: Atmospheric air contains far less oxygen content than the dissolved
oxygen in the water.

• A. Both the assertion and the reason are true, and the reason is a correct explanation of the assertion.
• B. Both the assertion and reason are true, but the reason is not a correct explanation of the assertion.
• C. Assertion is true but the reason is false.
• D. Assertion and reason are false.
• E. Assertion is false but reason is true.

Answer 1

Answer: (C)

Assertion is true but the reason is false.

1. Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. When taken out of the water, gills (the respiratory organ) stick together thereby reducing the surface area, leaving the blood vessels no longer exposed to oxygen in the air. So, it is correct that most of the fish do die of suffocation when out of the water and thus, the assertion statement is correct.
2. The atmospheric air contains far more oxygen content than water (air contain 21% oxygen and water contains 0.5 - 0.9% of dissolved oxygen by volume depending on the temperature). So, the statement is wrong and not a correct reason for the given assertion.

Hence, option C is correct.