Question

ocean water and the air constantly exchange gases. co₂ can enter ocean water directly from the atmosphere. after dissolving in water, co₂ may either be absorbed by organisms or sink deeper into the ocean. carbon in the deep ocean may be stored as sediments on the seafloor.
over time, carbon in the deep ocean is cycled back to the surface as the water circulates. co₂ at the oceans surface can move back into the air. but taken altogether, ocean activities are a net carbon sink.
select the true statements.
all of the co₂ at the oceans surface sinks deeper into the ocean.
co₂ from the atmosphere is absorbed by both ocean water and plants.
co₂ is constantly exchanged between the atmosphere and the ocean.
overall, the ocean absorbs more carbon than it releases.

Explanation:

1. Analyze the first statement: The text says "CO₂ at the ocean's surface can move back into the air", so not all CO₂ sinks deeper. So this statement is false.
2. Analyze the second statement: The text mentions CO₂ enters ocean water from the atmosphere, and plants (organisms) absorb CO₂, so this is true.
3. Analyze the third statement: The text says "Ocean water and the air constantly exchange gases" and CO₂ is part of that exchange, so this is true.
4. Analyze the fourth statement: The text says "ocean activities are a net carbon sink", meaning it absorbs more than it releases, so this is true.

Answer:

B. $\ce{CO_{2}}$ from the atmosphere is absorbed by both ocean water and plants.
C. $\ce{CO_{2}}$ is constantly exchanged between the atmosphere and the ocean.
D. Overall, the ocean absorbs more carbon than it releases.