SEMI FINALS SCIENCE 7

What is the most abundant element in the Earth's atmosphere?

•  Argon

• Carbon dioxide 

• Nitrogen 

• Oxygen

1.    What is the correct order of Earth's atmospheric layers from bottom to top?

•   Stratosphere, Mesosphere, Troposphere, Thermosphere, Exosphere

•   Stratosphere, Troposphere, Thermosphere, Mesosphere, Exosphere

• Troposphere, Mesosphere, Stratosphere, Thermosphere, Exosphere

•    Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere

Which layer of the atmosphere contains the ozone layer?

• Mesosphere    

•     Stratosphere

• . Thermosphere   

• Troposphere

  I

In which layer do virtually all weather phenomena take place?

I

• Exosphere         

•     Mesosphere       

• .            Stratosphere     

•   Troposphere

In which atmospheric layer is most water vapor found?

a.

• Troposphere         

• Stratosphere  

•                Mesosphere        

• Thermosphere

What is meant by ‘trace’ gases?

• They are not harmful.                   

• They are naturally occurring on Earth.

• They are emitted by trees. 

• They are present in very small amounts.

What is the basis for the division of the layers of the atmosphere surrounding Earth?

• Changing temperature                      

• Changing weather patterns

• b.  Changing amount of oxygen           

•      Changing composition of gases

Why is the presence of ozone above the troposphere important for the survival of living thing on Earth?

• It warms Earth’s surface.   

• It makes jet flying more comfortable.

• It helps in cloud formation.                    

• It offers protection from the Sun’s harmful UV rays.

The greenhouse effect is a natural phenomenon. Without a natural greenhouse effect, the temperature of the Earth would be about -18°C instead of its present 14°C. Why are scientists concerned about the greenhouse effect?

•   There is no technology that will keep the temperature of Earth constant.

•   Planting trees in wider areas is not possible; Earth has many desert areas.

• Human activities like burning of fossil fuels and deforestation enhance the greenhouse effect.

• The human population is increasing rapidly; more carbon dioxide will be released to the atmosphere.

Why do hikers put on thicker clothes when climbing a high mountain?

• For protection against insect bites

• The air temperature decreases with altitude

• So they can easily be located when they get lost

• To add more weight so they will not be pushed by the wind