Explanation

The percentage of oxygen in the air is about 20.95%.

The air is made up of many gases, including oxygen, nitrogen, argon, and carbon dioxide

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Nitrogen

Nitrogen is the most abundant gas in the air, making up about 78% of it. 

Argon

Argon is the third most abundant gas in the air, making up about 0.93% of it. 

Carbon dioxide

Carbon dioxide is present in trace amounts in the air, making up about 0.04% of it. 

Explanation

• The ozone layer is a layer of gas in the stratosphere that contains a high concentration of ozone (O3).
• It absorbs most of the sun's ultraviolet (UV) radiation, protecting the Earth from harmful UV rays.

Explanation

• Ozone gas is a molecule made up of three oxygen atoms, with the chemical formula O3.
• This is different from ordinary oxygen, which has the chemical formula O2.

Explanation

A food chain always begins with producers.

It usually green plants or algae, that make their own food through photosynthesis.

Explanation

• The greenhouse effect is an environmental problem caused by the increasing amount of carbon dioxide (CO2) in the atmosphere.
• Primarily due to human activities such as burning fossil fuels, deforestation, and land-use changes.
• This excess CO2 traps heat and leads to global warming and climate change.