Science exemplar problems class 9 Solutions for Chapter 14 natural resources

What happens when rain falls on soil without vegetational cover?

The nitrogen molecules present in air can be converted into nitrates and nitrites by

Among the given options, which one is not correct for the use of large amount of fertilisers and pesticides?

Which step is not involved in the carbon-cycle

Abdul, while driving to school, computes the average speed for his trip to be 20 km.h–1. On his return trip along the same route, there is less traffic and the average speed is 30 km.h–1. What is the average speed for Abdul’s trip?

One of the following processes is not a step involved in the water-cycle operating in nature ………………………….

A motorboat starting from rest on a lake accelerates in a straight line at a constant rate of 3.0 m s–2 for 8.0 s. How far does the boat travel during this time?

Total earth’s surface covered by water is

The term “water-pollution” can be defined in several ways. Which of the following statements does not give the correct definition?

Rainfall patterns depend on which of the following factors?

The two forms of oxygen found in the atmosphere are

How does the concentration of carbon dioxide in the atmosphere affect climate?

Which of the following factors does not lead to soil formation in nature?

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 ………………………….

Which of the following is not a green house gas?

Which of the following is a recently originated problem of environment?

The process of nitrogen-fixation by bacteria does not take place in the presence of ……………………………………………..

State TRUE or FALSE:

Top-soil contains humus, and living organisms.

Which of the following options gives the CORRECT path of CO₂ in the environment?

State TRUE or FALSE:

The major source of minerals in the soil is the parent rock from which soil is formed.

Biotic component of biosphere is not constituted by

Oxygen is returned to the atmosphere mainly by

An increase in carbon dioxide content in the atmosphere would not cause

Growth of Lichens on barren rocks is followed by the growth of

Low visibility during cold weather is due to

Marked temperature changes in aquatic environment can affect

Soil erosion can be prevented by

Oxygen is harmful for

The atmosphere of the earth is heated by radiations which are mainly

(a) radiated by the sun

(b) re-radiated by land

(c) re-radiated by water

(d) re-radiated by land and water

If there were no atmosphere around the earth, the temperature of the earth will

(a) increase

(b) go on decreasing

(c) increase during day and decrease during night

(d) be unaffected

What would happen, if all the oxygen present in the environment is converted to ozone?

(a) We will be protected more

(b) It will become poisonous and kill living forms

(c) Ozone is not stable, hence it will be toxic

(d) It will help harmful sun radiations to reach earth and damage many life forms.

One of the following factors does not lead to soil formation in nature

(a) the sun

(b) water

(c) wind

(d) polythene bags

The two forms of oxygen found in the atmosphere are

(a) water and ozone

(b) water and oxygen

(c) ozone and oxygen

(d) water and carbon-dioxide

The process of nitrogen-fixation by bacteria does not take place in the presence of

(a) molecular form of hydrogen

(b) elemental form of oxygen

(c) water

(d) elemental form of nitrogen

Rainfall patterns depend on

(a) the underground water table

(b) the number of water bodies in an area

(c) the density pattern of human population in an area

(d) the prevailing season in an area

Among the given options, which one is not correct for the use of large amount of fertilisers and pesticides?

(a) They are eco-friendly

(b) They turn the fields barren after some time

(c) They adversally affect the useful component from the soil

(d) They destroy the soil fertility

The nitrogen molecules present in air can be converted into nitrates and nitrites by

(a) a biological process of nitrogen fixing bacteria present in soil

(b) a biological process of carbon fixing factor present in soil

(c) any of the industries manufacturing nitrogenous compounds

(d) the plants used as cereal crops in field

One of the following processes is not a step involved in the water-cycle operating in nature

(a) evaporation

(b) transpiration

(c) precipitation

(d) photosynthesis

The term “water-pollution” can be defined in several ways. Which of the following statements does not give the correct definition?

(a) The addition of undesirable substances to water-bodies

(b) The removal of desirable substances from water-bodies

(c) A change in pressure of the water bodies

(d) A change in temperature of the water bodies

Which of the following is not a green house gas?

(a) Methane

(b) Carbon dioxide

(c) Carbon monoxide

(d) Ammonia

Which step is not involved in the carbon-cycle?

(a) Photosynthesis

(b) Transpiration

(c) Respiration

(d) Burning of fossil fuels

Ozone-hole’ means

(a) a large sized hole in the ozone layer

(b) thinning of the ozone layer

(c) small holes scattered in the ozone layer

(d) thickening of ozone in the ozone layer

Ozone-layer is getting depleted because of

(a) excessive use of automobiles

(b) excessive formation of industrial units

(c) excessive use of man-made compounds containing both fluorine and chlorine

(d) excessive deforestation.

Which of the following is a recently originated problem of environment?

(a) Ozone layer depletion

(b) Green house effect

(c) Global warming

(d) All of the above

When we breathe in air, nitrogen also goes inside along with oxygen. What is the fate of this nitrogen?

(a) It moves along with oxygen into the cells

(b) It comes out with the CO2 during exhalation

(c) It is absorbed only by the nasal cells

(d) Nitrogen concentration is already more in the cells so it is not at all absorbed.

Top-soil contains the following

(a) Humus and living organisms only

(b) Humus and soil particles only

(c) Humus, living organisms and plants

(d) Humus, living organisms and soil particles.

Choose the correct sequences

(a) CO2 in atmosphere → decomposers → organic carbon in animals → organic carbon in plants

(b) CO2 in atmosphere → organic carbon in plants → organic carbon in animals → inorganic carbon in soil

(c) Inorganic carbonates in water → organic carbon in plants → organic carbon in animals → scavengers

(d) Organic carbon in animals → decomposers → CO2 in atmosphere → organic carbon in plants

Major source of mineral in soil is the

(a) parent rock from which soil is formed

(b) plants

(c) animals

(d) bacteria

Total earth’s surface covered by water is

(a) 75%

(b) 60%

(c) 85%

(d) 50%

Biotic component of biosphere is not constituted by

(a) producers

(b) consumers

(c) decomposer

(d) air

An increase in carbondioxide content in the atmosphere would not cause

(a) more heat to be retained by the environment

(b) increase in photosynthesis in plants

(c) global warming

(d) abundance of desert plants

Oxygen is returned to the atmosphere mainly by

(a) burning of fossil fuel

(b) respiration

(c) photosynthesis

(d) fungi

Low visibility during cold weather is due to

(a) formation of fossil fuel

(b) unburnt carbon particles or hydrocarbons suspended in air

(c) lack of adequate power supply

(d) none of these

Growth of Lichens on barren rocks is followed by the growth of

(a) moss

(b) ferns

(c) gymnosperms

(d) algae

Marked temperature changes in aquatic environment can affect

(a) breeding of animals

(b) more growth of aquatic plants

(c) process of digestion in animals

(d) availability of nutrients.

Soil erosion can be prevented by

(a) raising forests

(b) deforestation

(c) excessive use of fertilizer

(d) overgrazing by animals

Oxygen is harmful for

(a) ferns

(b) nitrogen fixing bacteria

(c) chara

(d) mango tree

How do fossil fuels cause air pollution?

How can we prevent the loss of topsoil?

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 the coastal areas, wind current moves from the sea towards the land during the day; but during the 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 the formation of soil? Write the model 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 the 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 a mass mortality of fishes in a pond. What may be the reasons?

Lichens are called pioneer colonizers of bare rock. How can they help in the 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 the 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 to reducing water pollution.

A motor car, with its glass totally closed, is parked directly under the sun. The inside temperature of the car rises very high. Explain why?

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?