The present atmospheric concentration of carbon dioxide is approximately 396 ________.
A) parts per hundred
B) parts per thousand
C) parts per million
D) parts per billion
E) parts per trillion

Question

Quizplus · Accepted Answer

The atmospheric concentration of carbon dioxide is usually measured in parts per million (ppm), which means for every million air molecules, approximately 396 of them are carbon dioxide molecules. Therefore, choice C, parts per million, is the correct option.

The Present Atmospheric Concentration of Carbon Dioxide Is Approximately 396