Dual Enrollment Environmental Science Practice Exam 2026 - Free Environmental Science Practice Questions and Study Guide

Greenhouse gases trap heat by absorbing infrared radiation emitted by Earth's surface, helping keep the lower atmosphere warmer. Carbon dioxide fits this role because its molecular structure absorbs infrared radiation in specific vibrational bands, contributing to the atmospheric heat balance. Oxygen and nitrogen are diatomic molecules with symmetric, nonpolar structures, so they do not absorb infrared radiation effectively and have little direct greenhouse effect. Nitric oxide is reactive and not a major long-lived heat-trapping gas like CO2 in the atmosphere. So carbon dioxide is the primary greenhouse gas among these options.