Question

which of the following is a reservoir for carbon and nitrogen, but not phosphorus?
land
ocean
atmosphere
done

Explanation:

To determine the reservoir for carbon and nitrogen but not phosphorus, we analyze each option:

• Land: Contains phosphorus (e.g., in soil minerals, organic matter), so it's not the answer.
• Ocean: Has phosphorus (e.g., in marine sediments, dissolved forms), so it's not the answer.
• Atmosphere: Carbon is present as $CO_2$, nitrogen as $N_2$ (and other nitrogen - containing gases). Phosphorus has no significant gaseous form in the atmosphere, so it is a reservoir for carbon and nitrogen but not phosphorus.

Answer:

C. atmosphere