Which of the following is true of carbon dioxide?

Question

Quizplus · Accepted Answer

Carbon dioxide levels have increased and exceeded the natural range of 180 to 300 parts per million (ppm) in recent years, mostly due to human activities such as burning of fossil fuels.

Answer: C
 Carbon dioxide is only a small fraction of the Earth's atmosphere (about 0.04%), much smaller compared to nitrogen (78%) and oxygen (21%).

Answer: None of the above
 Option A is incorrect because carbon dioxide plays a significant role in the Earth's temperature regulation, functioning as a greenhouse gas. Option D is also incorrect because atmospheric CO2 has actually increased in recent decades, not decreased.

Which of the Following Is True of Carbon Dioxide