Ozone in the upper atmosphere has been depleted by
a. carbon dioxide.
b. chlorofluorocarbons.
c. sulfur dioxide.
d. oxygen

Ozone in the upper atmosphere has been depleted by

B. chlorofluorocarbons

According to the question, Ozone in the upper atmosphere has been depleted by chlorofluorocarbons

Ozone is a form of molecular oxygen and it exists in the upper atmosphere predominantly. It is formed when oxygen is absorbed by the sun-short UVC and then breaking down by some chemicals such as chlorine from chlorofluorocarbons.

Scientist put together some evidences in the early 1980s to support the fact that ozone layer depletion was as a result of the overabundance of chlorofluorocarbons in the atmosphere.  

In industries, chlorofluorocarbons are used as refrigerants, which insulate foam and solvent. However, winds carry chlorofluorocarbons into the stratosphere in a process that could take up to 2-5 years. Chlorofluorocarbons releases chlorine when breaking down into the atmosphere and the chlorine attacks ozone.  

The 1920s was a period when refrigerators and air conditioning systems used compounds such as propane, chloromethane, ammonia as refrigerants. Although this compound were very effective but they are very toxic and flammable. Individuals that come in contact with this compound could have a serious injury or death.

However, because of the danger these compound poses, a team of chemists came together to developed nonflammable and nontoxic compounds that are alternative to the refrigerants.  

Compound that contains Carbons and halogens such as chlorine and fluorine were the two compounds the team focused on.

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Mars

Explanation:

In the 1960s, humans set out to discover what the red planet has to teach us. Now, NASA is hoping to land the first humans on Mars by the 2030s. Mars has captivated humans since we first set eyes on it as a star-like object in the night sky.

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