Which gases are considered greenhouse gases?

Greenhouse gases are those that can absorb and emit infrared radiation, contributing to the greenhouse effect, which warms the Earth's atmosphere. The correct option includes carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), all of which are significant contributors to this effect.

Carbon dioxide is released through natural processes such as respiration and volcanic eruptions, as well as human activities like burning fossil fuels. Methane, while less abundant in the atmosphere than carbon dioxide, is much more effective at trapping heat — it can absorb 84 times more heat than CO2 over a 20-year period. Nitrous oxide has similar properties and is primarily released from agricultural and industrial activities.

In contrast, the other options include gases that either do not have a significant impact on the greenhouse effect or are not greenhouse gases at all. Water vapor can be a greenhouse gas but is not listed in the correct choice. NaCl (sodium chloride) is a solid at room temperature and does not contribute to atmospheric warming. Gases like argon (Ar), chlorine (Cl2), and fluorine (F2) also lack the properties needed to effectively absorb infrared radiation in significant amounts, making them non-contributors to the greenhouse effect. Helium