Question

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40. Which one of the following statements is correct ?
1) Upto about 15 km above the earth's surface, ozone is beneficial to life but
chlorofluorocarbons are harmful
3) Beyond about 20 km above the earth's surface, presence of ozone is vital to
life on earth and chlorofluorocarbons are beneficial
3) Beyond about 20 km above the surface of earth, ozone is vital to life on earth.
but chlorofluorocarbons are harmful
4) Upto 15 km above the earth's surface both ozone and chlorofluorocarbons
are harmful to life​

Answer 1

Answer:

1 number is the correct one