- 05/17/2019 at 6:23 am #875548EduGorillaKeymasterSelect Question Language :
Chlorofluorocarbons (CFCs), chemicals found mainly in
spray aerosols heavily used by industrialized nations
for much of the past 50 years, are the primary culprits
in ozone layer breakdown. When CFCs reach the upper
atmosphere, they are exposed to ultraviolet rays,
which cause them to break down into substances that
include chlorine. The chlorine reacts with the oxygen
atoms in ozone and rips apart the ozone molecule. One
atom of chlorine can destroy more than a hundred
thousand ozone molecules, according to the U.S.
Environmental Protection Agency. About 90 percent of
CFCs currently in the atmosphere were emitted by
industrialized countries in the Northern Hemisphere,
including the United States and Europe. These
countries banned CFCs by 1996, and the amount of
chlorine in the atmosphere is falling now. But scientists
estimate it will take another 50 years for chlorine
levels to return to their natural levels.
The author says that CFCs are primary culprits
in ozone layer breakdown. Which of the
following is not a valid reason for this?
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They are released by the industrialised nations.
They release chlorine which reacts with the oxygen atoms in ozone.
They can destroy thousands of ozone molecules.
The chlorine released by them can stay in the atmosphere for long duration.
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