Answer:

WHAT I HAVE LEARNED?

1.Earth's atmosphere is composed of about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases. Trace amounts of carbon dioxide, methane, water vapor, and neon are some of the other gases that make up the remaining 0.1 percent.

2. OZONE LAYER

The ozone layer is a region of high ozone concentration in the stratosphere, 15 to 35 kilometres above Earth's surface. The ozone layer acts as an invisible shield and protects us from harmful ultraviolet (UV) radiation from the sun.

3.The majority of the mass of the entire atmosphere is contained in the troposphere between approximately 75 and 80 percent. Most of the water vapor in the atmosphere, along with dust and ash particles, are found in the troposphere explaining why most of Earth's clouds are located in this layer.

4.A molecule of ozone (O3) contains three oxygen (O) atoms bound together. Oxygen molecules (O2), which constitute 21% of Earth's atmosphere, contain two oxygen atoms bound together.

5.The main cause of ozone depletion and the ozone hole is manufactured chemicals, especially manufactured halocarbon refrigerants, solvents, propellants, and foam- blowing agents (chlorofluorocarbons (CFCs), HCFCs, halons), referred to as ozone-depleting substances (ODS).