Question

The percentage of carbon dioxide in the atmosphere is____ppm

• A. 345 ppm
• B. 435 ppm
• C. 534 ppm
• D. 543 ppm

Hint:

Carbon dioxide levels are measured in ppm (parts per million), whereas Oxygen and Nitrogen are measured in percentages.

Answer 1

The Correct Option is A

Step 1: Concept
The concentration of gases in the atmosphere is often measured in parts per million (ppm).

Step 2: Meaning
Carbon dioxide ($CO_2$) is a trace gas that plays a significant role in the Earth's greenhouse effect.

Step 3: Analysis
While atmospheric $CO_2$ levels have been rising over the last few decades, historical and standardized textbook values often cite approximately 345 ppm to 400 ppm depending on the year of the data.

Step 4: Conclusion
Based on the provided options, 345 ppm is the identified correct value.
Final Answer: (A)