Three-fourths of every air stays in the troposphere, the lowest layer the the earth’s atmosphere. Waiting is a mixture that gases, most of i m sorry are naturally occurring. Air also contains a significant amount that human-made air pollutants, including some that room not for sure to breathe and also some that heat our planet’s climate. The troposphere likewise contains water in all three phases (liquid, solid, and gas) as well as solid particles, referred to as aerosols.

You are watching: Which one of the following is the most abundant gas in the atmosphere?


The dry composition the the setting is mostly nitrogen and oxygen. It also contains fractional amounts of argon and also carbon dioxide and also trace amounts of other gases, such as helium, neon, methane, krypton, and hydrogen (NASA). Credit:


The most abundant naturally emerging gas is Nitrogen (N2), which renders up around 78% of air. Oxygen (O2) is the 2nd most numerous gas at about 21%. The inert gas Argon (Ar) is the third most plentiful gas at .93%. Over there are likewise trace quantities of carbon dioxide (CO2), neon (Ne), helium (He), methane (CH4), krypton (Kr), hydrogen (H2), nitrous oxide (NO), xenon (Xe), ozone (O3), iodine (I2), carbon monoxide (CO), and also ammonia (NH3) in the atmosphere.

Water Vapor

Due to the water cycle, the quantity of water in the wait is continually changing. The reduced troposphere can contain approximately 4% water vapor (H2O) in locations near the tropics, while the poles contain just trace amounts of water vapor. The concentration of water vapor decreases drastically with altitude. The top troposphere has substantially less water vapor than air close to the surface, the stratosphere and mesosphere have almost no water vapor, and the thermosphere contains none at all.


Air likewise contains small solid particles called aerosols, such together dust, sea salt, and ash native erupting volcanoes or forest fires. Numerous of these particles room so tiny that they are microscopic. Rather are huge enough come see. Aerosols impact climate by help clouds kind and shading the planet by scattering or absorbing sunlight. In the critical century, manufacturing and also widespread use of burning engines have increased the variety of aerosols in the environment as particulate matter spews native smokestacks and also exhaust pipes. Burning wood and also other materials also include particles to the air.

Atmospheric Chemistry

Like whatever on Earth, the waiting is made of chemicals. The chemicals in the air often incorporate with each other, or with various other chemicals from the earth surface, through chemical reactions. Plenty of of these chemical reactions assist maintain healthy natural environments and are vital for plants and also animals. Nitrogen gas in the atmosphere does almost nothing, but nitrogen elsewhere on earth is vital for life. With the nitrogen cycle, nitrogen provides its method into soil and also water, binding with various other elements, and also can be offered by living things. Oxygen indigenous the atmosphere causes oxidation reactions that help malfunction matter and release nutrients right into soils, and is offered by humans and animals in to move respiration.

Atmospheric chemistry in the troposphere is also influenced through human-made chemicals that have the right to negatively impact human health and also the environment. Because that example:

Smog, which is greatly made of ozone and also particulate carbon (soot) emitted through coal-burning strength plants, causes damage come the lungs of humans and also animals. Factories the burn fossil fuels likewise release sulfur and also nitrogen dioxides, which integrate with water in the atmosphere to make acid rain. Mountain rain causes damage come natural and also human-made environments.

Chemistry of the Air

The table listed below lists the significant gas components and their function in the atmosphere. Click each molecule name to learn more about them.

GasChemical & MolecularStructureRole in the setting



78% of the air in the atmosphere is nitrogen. Nitrogen is transferred to plants, animals, and the atmosphere through the nitrogen cycle.

Nitrogen Oxides


Nitrogen oxides space air pollutants that add to the development of ozone. They additionally create nitric acid, which is component of acid rain, once they mix through water droplets in the air.



Oxygen makes up 21% that the atmosphere. The is extremely reactive and forms compounds with plenty of other chemicals, and also is necessary for respiration in living things.



Ozone in the troposphere is a human-made pollutant. Ozone in the stratosphere creates the ozone layer, i beg your pardon is crucial for the survival of life at the earth surface.



Argon renders up around 1% the the atmosphere and also comes largely from the degeneration of potassium in the earth’s crust. It is an inert gas, which means that it does no react with various other chemicals.

Water Vapor


Water is cycled through every one of Earth’s solution in each of its three phases: solid, liquid, or gas. Water vapor in the environment is a greenhouse gas because of its heat-trapping ability.

Carbon Dioxide

Carbon dioxide normally composes around .03% that the atmosphere, however the lot is increasing due to the burning of fossil fuels. Plants and eubacteria use carbon dioxide during photosynthesis. Humans, various other animals, and also plants add it come the air with respiration. Carbon dioxide is a heat-trapping greenhouse gas.

Carbon Monoxide


Carbon monoxide in the air comes from burning fuel in vehicles, volcanoes, and forest fires. The is a gift gas.



Methane gas is released into the air from landfills, livestock and their manure, and also from oil and gas wells. The is likewise created as soon as organic material decomposes. The is a heat-trapping greenhouse gas.

See more: Can A Right Triangle Have An Obtuse Angle, Acute, Right, And Obtuse Triangles

Sulfur Oxides


Sulfur oxides are developed when coal and also oil room burned. It’s additionally released indigenous volcanoes. The sulfur oxides mix v water droplets in the setting to produce sulfuric acid, which is a ingredient of acid rain.