Among the following greenhouse gases, which one has the greatest heat trapping ability per molecule and is therefore especially powerful in contributing to global warming?

Introduction / Context:
Climate change and global warming are closely linked to the presence of greenhouse gases in the atmosphere. Different gases trap heat with different effectiveness. This question asks which greenhouse gas among the options has the greatest heat trapping ability per molecule, often described in terms of global warming potential. Understanding this helps students appreciate why some gases, even at low concentrations, can have a large impact on climate.

Given Data / Assumptions:

• We are comparing greenhouse gases by their heat trapping ability per molecule, not by total quantity in the atmosphere.
• The options include common greenhouse gases and related compounds.
• Carbon dioxide is the most abundant anthropogenic greenhouse gas but not the strongest per molecule.
• Chlorofluorocarbons are present in much smaller amounts but have very high global warming potential.

Concept / Approach:
Global warming potential is a measure of how much heat a greenhouse gas traps in the atmosphere compared to carbon dioxide over a specific time period. By this measure, many chlorofluorocarbons (CFCs) have extremely high global warming potential, often thousands of times greater than that of carbon dioxide. Methane and nitrous oxide also have higher global warming potential than carbon dioxide, but typically less than many CFCs. Therefore, when asked which gas has the greatest heat trapping ability among the listed options, chlorofluorocarbon is the correct choice.

Step-by-Step Solution:

Verification / Alternative check:
Environmental science texts often provide tables of global warming potential values for different gases. While the exact numbers vary from one CFC to another, many values are in the range of thousands of times that of carbon dioxide. Methane is commonly in the tens, and nitrous oxide in the hundreds, but CFCs usually exceed these significantly. Carbon dioxide, although very important due to its quantity, has a much lower global warming potential per molecule. This comparison confirms that chlorofluorocarbon is the strongest heat trapping gas among the listed choices.

Why Other Options Are Wrong:

• Nitrous oxide: Stronger than carbon dioxide and methane in warming potential, but generally weaker per molecule than many CFCs.
• Methane: Has higher heat trapping ability than carbon dioxide but less than nitrogen oxides and most CFCs.
• Carbon dioxide: The most discussed greenhouse gas due to its abundance, but not the strongest per molecule.
• Ozone in the lower atmosphere: Acts as a greenhouse gas and pollutant but still does not usually exceed the per molecule heat trapping ability of CFCs.

Common Pitfalls:
Students often confuse the total impact of a gas, which depends on both its global warming potential and its concentration, with the heat trapping ability per molecule. Because carbon dioxide is discussed so much, some learners assume it must be the strongest greenhouse gas. Others may focus only on methane. To avoid this, it is useful to remember that CFCs, although present in much smaller amounts, have very high global warming potential and therefore are extremely powerful greenhouse gases molecule for molecule.

Final Answer:
The greenhouse gas with the greatest heat trapping ability per molecule among the options is Chlorofluorocarbon.