Which percent of Earth's atmosphere does carbon dioxide gas make up? (1 point)
O less than 1 percent
O more than 99 percent
about 78 percent
O about 21 percent
less than 1 percent
To determine which percent of Earth's atmosphere carbon dioxide gas makes up, we need to examine the composition of the atmosphere. The Earth's atmosphere is made up of primarily nitrogen (about 78 percent) and oxygen (about 21 percent). The remaining approximately 1 percent consists of trace gases, including carbon dioxide (CO2) along with others such as argon, methane, ozone, and water vapor.
Therefore, the correct answer is "less than 1 percent" since it is included in the category of trace gases that make up the remaining portion of the atmosphere.