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Question
Assertion :An equilibrium is established between generation and destruction of ozone, leading to a steady state concentration of ozone layer in the stratosphere at an altitude of 20-30 km above sea level. Reason: The thickness of the ozone layer is generally larger above the equator and smaller above the poles.
Assertion :An equilibrium is established between generation and destruction of ozone, leading to a steady state concentration of ozone layer in the stratosphere at an altitude of 20-30 km above sea level. Reason: The thickness of the ozone layer is generally larger above the equator and smaller above the poles.
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Solution
The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
Ozone layer or shield is present in the stratosphere. It is also called
ozonosphere. Ozonosphere lies at altitude of 23-25 km over equator and
at slightly lower altitude elsewhere with 11-16 km height over poles.
90% of atmospheric ozone is present in ozonosphere. Thickness of ozone
is measured in Dobson units (D.U). An equilibrium is established between
generation and destruction of ozone, leading to a steady state
concentration of ozone layer in the stratosphere.
O3⇌O2+[O]
Of
late, this equilibrium (or balance) has been disrupted due to
enhancement of ozone degradation by ozone depleting substance (ODS).
Ozone layer present in stratosphere (good ozone) is vitally important to
life as it absorbs harmful UV radiations coming from sun. The total
thickness of ozone it condensed is 0.29 cm above equator and 0.40 cm
above poles towards the end of winter. Protection from UV radiations is
proportional to thickness of ozone layer.
Therefore, maximum amount
of UV radiations passing through the atmosphere reaches the earth's
surface in the tropics (i.e., near the equator) and this amount
decreases towards the poles.
So, the correct answer is 'Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion'.
Ozone layer or shield is present in the stratosphere. It is also called ozonosphere. Ozonosphere lies at altitude of 23-25 km over equator and at slightly lower altitude elsewhere with 11-16 km height over poles. 90% of atmospheric ozone is present in ozonosphere. Thickness of ozone is measured in Dobson units (D.U). An equilibrium is established between generation and destruction of ozone, leading to a steady state concentration of ozone layer in the stratosphere.
O3⇌O2+[O]
Of late, this equilibrium (or balance) has been disrupted due to enhancement of ozone degradation by ozone depleting substance (ODS). Ozone layer present in stratosphere (good ozone) is vitally important to life as it absorbs harmful UV radiations coming from sun. The total thickness of ozone it condensed is 0.29 cm above equator and 0.40 cm above poles towards the end of winter. Protection from UV radiations is proportional to thickness of ozone layer.
Therefore, maximum amount
of UV radiations passing through the atmosphere reaches the earth's
surface in the tropics (i.e., near the equator) and this amount
decreases towards the poles.
So, the correct answer is 'Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion'.
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