Correct Option
The correct option is (c).
Explanation
Carbon Dioxide (CO2) is a naturally occurring gas in the Earth's atmosphere. It plays a critical role in the carbon cycle, involving processes such as photosynthesis, respiration, and combustion. Understanding the reactants and products of these chemical reactions is essential to identifying the correct properties of the gas.
Statement-wise Analysis
- Statement 1 is Incorrect: Combustion (burning) is a chemical process where a substance reacts rapidly with oxygen and gives off heat. During the burning of carbon-based fuels (such as wood, coal, or petrol), oxygen is consumed from the atmosphere, and Carbon Dioxide is produced (released) as a byproduct, not consumed.
- Statement 2 is Correct: Respiration is the metabolic process by which living organisms produce energy. In aerobic respiration, glucose reacts with oxygen to release energy, producing water and Carbon Dioxide as waste products. Therefore, CO2 is generated during respiration.
- Statement 3 is Correct: Since Carbon Dioxide is a byproduct of cellular respiration, it is transported by the blood to the lungs to be expelled from the body. Consequently, the air we exhale contains a significantly higher concentration of Carbon Dioxide (approximately 4-5%) compared to the air we inhale (approximately 0.04%).
Key Takeaway
Combustion and Respiration both consume Oxygen and release Carbon Dioxide. Conversely, Photosynthesis consumes Carbon Dioxide and releases Oxygen.