### Correct Option: D. The relative amount of carbon dioxide present is increased. #### Detailed Explanation: When charcoal (which is primarily carbon) is ignited in the presence of air, a combustion reaction occurs. The primary components of air are nitrogen (approximately 78%) and oxygen (approximately 21%). During combustion, the carbon in the charcoal reacts with the oxygen in the air to produce carbon dioxide (CO₂) and heat. The chemical reaction can be represented as follows: \[ \text{C (s)} + \text{O}_2 (g) \rightarrow \text{CO}_2 (g) \] 1. **Combustion Process**: - When charcoal is ignited, it reacts with the oxygen in the air. This reaction consumes oxygen and produces carbon dioxide as a byproduct. - As the charcoal burns, the amount of oxygen in the cylinder decreases because it is being used up in the reaction. 2. **Relative Amount of Carbon Dioxide**: - As carbon dioxide is produced, its concentration in the cylinder increases. This means that, relative to the other gases present (mainly nitrogen and any remaining oxygen), the amount of carbon dioxide increases. - Therefore, the correct answer is D: the relative amount of carbon dioxide present is increased. #### Why the Other Options are Incorrect: - **Option A: The total volume of air is increased**: - This option is incorrect because the total volume of air does not increase. Instead, the combustion process consumes oxygen, which reduces the amount of oxygen in the air. The total volume of gases may change slightly due to temperature and pressure changes, but the overall volume of air remains constant unless gases are added or removed from the system. - **Option B: The relative amount of oxygen present is increased**: - This option is also incorrect. During combustion, the oxygen is consumed to produce carbon dioxide. Therefore, the relative amount of oxygen present actually decreases as the reaction proceeds. - **Option C: The relative amount of nitrogen present is decreased**: - This option is incorrect as well. Nitrogen is largely inert and does not participate in the combustion reaction. While the total volume of gases may change slightly, the relative amount of nitrogen remains essentially unchanged because it is not consumed in the reaction. #### Common Pitfalls: - Students may confuse the terms "relative amount" and "total amount." It is crucial to understand that while the total volume of gases may change due to temperature and pressure, the relative amounts of specific gases depend on their consumption or production during the reaction. - Misunderstanding the role of nitrogen in combustion can lead to incorrect conclusions about its relative amounts. ### Revision Summary: - When charcoal burns, it reacts with oxygen to produce carbon dioxide. - The combustion process decreases the amount of oxygen and increases the amount of carbon dioxide in the air. - The total volume of air does not increase; it remains constant unless gases are added or removed. - Nitrogen remains largely unchanged during the combustion process, as it does not react with carbon or oxygen.