Question

Which of the following gases protect us from the harmful sun rays?
A.Carbon Dioxide
B.Nitrogen
C.Ozone
D.None of these

Answer 1

Hint: The Earth is the only planet in the solar system that can sustain life. This mainly because of the blanket of gases that make the atmosphere which provides the air that we breathe and also protects us from the blasts of heat and radiation emanating from the sun. It helps to keep the planet warm during the day and cool at night.

Complete answer: Option A: is incorrect. Carbon dioxide makes up 0.04% of the earth’s atmosphere. It plays an important role in photosynthesis through which green plants convert carbon dioxide and water into food compounds, such as glucose, and release oxygen which can then be inhaled by animals to breathe. Respiration is the reverse of this process that is carried out by animals converting the food compounds by combining it with oxygen to release carbon dioxide and water. Carbon dioxide also traps heat from the earth’s surface to re-radiate it back to the surface and maintain a warm climate.
Option B: is incorrect. Nitrogen makes up 78% of the earth’s atmosphere. It helps maintain the nitrogen cycle by converting into multiple chemical forms as it circulates in the atmosphere, terrestrial and marine ecosystems through the process of fixation, ammonification, nitrification and denitrification.
Option C: is correct. Ozone is a gas made up of three oxygen atoms that are abundantly found in the stratosphere. This ozone is formed naturally through the interaction of solar ultraviolet (UV) radiation with molecular oxygen and forms the ozone layer in the stratosphere. This layer is 10-50 km above the Earth’s surface and its function is to reduce the amount of harmful UV radiation reaching the Earth's surface.
Option D: is incorrect.

Hence, The correct answer is Option C.

Note: The earth’s atmosphere extends up to over 480 km from the surface and is categorised into separate layers with different characteristics— troposphere, stratosphere, mesosphere, thermosphere and exosphere.