The atmosphere of the earth is heated by radiations which are mainly
If there were no atmosphere around the earth, the temperature of the earth will
What would happen, if all the oxygen present in the environment is converted to ozone?
One of the following factors does not lead to soil formation in nature
The two forms of oxygen found in the atmosphere are
The process of nitrogen-fixation by bacteria does not take place in the presence of
Rainfall patterns depend on
Among the given options, which one is not correct for the use of large amount of fertilisers and pesticides?
The nitrogen molecules present in air can be converted into nitrates and nitrites by
One of the following processes is not a step involved in the water-cycle operating in nature
The term “water-pollution” can be defined in several ways. Which of the following statements does not give the correct definition?
Which of the following is not a greenhouse gas?
Which step is not involved in the carbon-cycle?
‘Ozone-hole’ means
Ozone-layer is getting depleted because of
Which of the following is a recently originated problem of environment?
When we breathe in air, nitrogen also goes inside along with oxygen. What is the fate of this nitrogen?
Top-soil contains the following
Choose the correct sequences
Major source of mineral in soil is the
Total earth’s surface covered by water is
Biotic component of biosphere is not constituted by
An increase in carbon dioxide content in the atmosphere would not cause
Oxygen is returned to the atmosphere mainly by
Low visibility during cold weather is due to
Growth of Lichens on barren rocks is followed by the growth of
Marked temperature changes in aquatic environment can affect
Soil erosion can be prevented by
What happens when rain falls on soil without vegetational cover?
Oxygen is harmful for
Rivers from land, add minerals to sea water. Discuss how?
How can we prevent the loss of top layer of soil?
How is the life of organisms living in water affected when water gets polluted?
During summer, if you go near the lake, you feel relief from the heat, why?
In coastal area, wind current moves from the sea towards the land during day; but during night it moves from land to the sea. Discuss the reason.
Following are a few organisms
(a) lichen (b) mosses
(c) mango tree (d) cactus
Which among the above can grow on stones; and also help in formation of soil? Write the mode of their action for making soil.
Soil formation is done by both abiotic and biotic factors. List the names of these factors by classifying them as abiotic and biotic?
All the living organisms are basically made up of C, N, S, P, H and O. How do they enter the living forms? Discuss.
Why does the percentage of gases like oxygen, nitrogen and carbon dioxide remain almost the same in the atmosphere?
Why does moon have very cold and very hot temperature variations eg, from -190°C to 110°C even though it is at the same distance from the sun as the earth is?
Why do people love to fly kites near the seashore ?
Why does Mathura refinery pose problems to the Taj Mahal?
Why do not lichens occur in Delhi whereas they commonly grow in Manali or Darjeeling?
Why does water need conservation even though large oceans surround the land masses?
There is mass mortality of fishes in a pond. What may be the reasons?
Lichens are called pioneer colonisers of bare rock. How can they help in formation of soil?
“Soil is formed by water.” If you agree to this statement then give reasons
Fertile soil has lots of humus. Why?
Why step farming is common in hills?
Why are root nodules useful for the plants?
How do fossil fuels cause air pollution?
What are the causes of water pollution? Discuss how you can contribute in reducing water pollution.
A motor car, with its glass totally closed, is parked directly under the sun.
Justify “Dust is a pollutant” ?
Explain the role of the Sun in the formation of soil.
Carbon dioxide is necessary for plants. Why do we consider it as a pollutant?