The ozone layer is found in which layer of the atmosphere? MCQ with Answer and Explanation

The ozone layer is found in which layer of the atmosphere?
A. Stratosphere
B. Mesosphere
C. Thermosphere
D. Troposphere
Answer: Option A
Solution (By JKExamLibrary)
The ozone layer is located in the lower stratosphere (~15-35 km altitude), where ozone concentration is highest. It absorbs harmful ultraviolet radiation (UV-B and UV-C) from the sun. Ground-level ozone (troposphere) is a pollutant and component of smog, harmful to health. Ozone depletion is caused by chlorofluorocarbons (CFCs) which release chlorine atoms that catalytically destroy O₃.

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Practice More chemistry Questions

Question #1
The unit of electrochemical equivalent (Z) is:
A. g/mol
B. C/g
C. g/C (gram per coulomb)
D. C/mol

Correct Answer: Option C


Explanation:
From Faraday's first law, m = ZQ, so Z = m/Q. SI unit is kg/C, but practical unit is g/C. It is the mass of substance liberated per unit charge.

This question belongs to: Science chemistry
Question #2
Which bacterium is used as a biofertilizer for fixing atmospheric nitrogen in non-leguminous crops?
A. Nitrosomonas
B. Nitrobacter
C. Rhizobium
D. Azotobacter

Correct Answer: Option D


Explanation:
Azotobacter is a free-living aerobic bacterium that fixes atmospheric nitrogen in the soil, making it available to non-leguminous crops. Rhizobium is symbiotic and specific to legumes. Nitrobacter and Nitrosomonas are involved in nitrification (converting ammonia to nitrites/nitrates), not nitrogen fixation.

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Question #3
Which process is used to concentrate sulfide ores?
A. Leaching with NaOH
B. Froth flotation
C. Magnetic separation
D. Calcination

Correct Answer: Option B


Explanation:
Froth flotation separates sulfide ore particles from gangue by using oil and water. The ore particles adhere to the froth and float, while gangue sinks. Used for ZnS, PbS, CuFeS₂. Magnetic separation for magnetite, leaching for bauxite.

This question belongs to: Science chemistry