From which compound plants obtain their carbon and most of their oxygen.

Answer

**Step-by-Step Solution:**

1. **Understanding Plant Nutrition**: Plants are classified as autotrophs, meaning they produce their own food through a process called photosynthesis.

2. **Photosynthesis Process**: The basic equation for photosynthesis is:
\[ 6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2 \]
This indicates that carbon dioxide (CO2) and water (H2O) are the raw materials used by plants to produce glucose (C6H12O6) and oxygen (O2).

3. **Source of Carbon and Oxygen**: In the photosynthesis equation, carbon dioxide (CO2) is the compound from which plants obtain their carbon. Additionally, the oxygen produced during photosynthesis comes from the splitting of water molecules, but the majority of the oxygen released is derived from the carbon dioxide used in the process.

4. **Conclusion**: Therefore, plants obtain their carbon and most of their oxygen from carbon dioxide (CO2) present in the atmosphere.

**Final Answer**: Plants obtain their carbon and most of their oxygen from carbon dioxide (CO2) in the atmosphere.

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