Saturday, January 31, 2015

Natural Resources class 9 CBSE NCERT Questions with solutions

CBSE NCERT Questions with solutions

Q. State the role of the atmosphere in climate control?

Ans: Atmosphere prevents sudden increase in temperature during the day light hours. It slows down the escape of heat into outer space during the night.
Q. How is acid rain caused ?

Ans: The fossil fuels like coal and petroleum/contain small amounts of nitrogen and sulphur/When the fossil fuels are burnt,/nitrogen and sulphur are burnt/and produces different oxides of nitrogen and sulphur/When these oxides dissolve in rain it gives rise to acid rain.

Q. What are the different ways in which water gets polluted ? How does it affect the life forms ?

Ans: (a) The addition of undesirable substances like fertilizers and pesticides, mercury salts in water/can cause cholera produced by the bacteria.

(b) The removable of desired substances like oxygen from the water/adversely affect the aquatic organisms.

(c) A sudden change in temperature in water bodies/would be dangerous and effect their breeding. The eggs and larvae are affected by the change in temperature.

Q. What are the biogeochemical cycles ? Name the gas that is incorporated into life forms through photosynthesis.

Ans: The transfer of energy and matter between the biotic components of the biosphere is called biogeochemical cycle.

The gas that is incorporated into life forms through photosynthesis is carbondioxide

Q. What is the function of humus in soil?
Ans: Humus cause the soil to become more porous and allows water and air to penetrate deep underground.

Q. List the causes that affect the life forms that are found in water bodies in various ways. Name the element present in coal other than carbon that releases harmful gases during combustion of coal.

Ans:(i) Excess of fertilizers and pesticides used in the farms are washed into water bodies.

(ii) Dumping of sewage from dwelling places into water bodies

(iii) Release of hot water contaminated water from industries.

(iv) Release of water from dams affect the temperature of river.

(b) Sulphur and nitrogen

Q. Explain how the nitrogen molecules are converted into nitrates and nitrites by  (i) Biological Process (ii) Physical process.

Ans: Biological process : Nitrogen fixing bacteria found in the root nodules of the legumes convert nitrogen molecules to nitrates and nitrites.

Physical process : During lightning, the high temperature and pressure created in the air convert nitrogen into oxides of nitrogen. These oxides dissolve in water to give nitric and nitrous acids. These acids when falls to land form nitrates and nitrites.

Q. What is the main cause of increase in CO2 in atmosphere ? Explain the harmful effect of increase in CO2 content in atmosphere

Ans: Industrial revolution is the main cause of increase in carbon dioxide in the atmosphere.

Increase in carbon dioxide gives rise to green house effect. This increases global warming. This causes imbalance in nature, affects monsoons and rainfall.

Q. What is ozone hole ? Where is it found ? What is its effect ?
Ans: (a) In the upper regions of the atmosphere there is a layer of ozone , which gets deflected due to chlofluro carbons and created a hole that is called ozone hole.

(b) it is found above antartica/over north pole

(c) UV radiation will reach the earth and cause disease – cancer, reduce immunity, reduce crop yield.

Q. (a) 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 ?
(b) Why lichens do not occur in Delhi whereas they commonly grow in Manali or Darjeeling ?

(c) How are root modules useful for the plants ?

Ans: (a) Glass trap sunlight that heats up the interior. Since glass is an insulator heat waves do not escape. Thus, Interior of the car becomes very hot similar to glass house effect.

(b) Lichens are sensitive to sulphur dioxide which occur in sufficient quantity in Delhi. Delhi is semi arid – atmosphere and moisture is very low. In Manali and Darjeeling atmosphere is Humid. Sulphur dioxide pollution comparatively low.

(c) Root nodules contain Nitrogen fixing bacteria. Nitrogen from atmosphere is converted into organic compounds in soil.

Q. Why is step farming common in hills ?

Ans This is because step farming prevents soil erosion from the fast flowing water

Q. Which cycle is known as the perfect cycle in biosphere? Why?
Ans. Nitrogen cycle is known as the perfect cycle in biosphere as it maintains the over all amount of nitrogen constant in atmosphere, water and soil.

Natural Resources class 9 CBSE NCERT Solved Questions with solutions
CCE Test Paper Biology Chapter Natural Resources ix Biology-1
CCE Test Paper Biology Chapter Natural Resources ix Biology-2
CBSE Class 9th natural resources Solved Board Questions 
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natural resources class 10

Sunday, January 25, 2015

CBSE Class 10 - SA2 Mathematics Solved Sample Paper march 2015

CBSE Class 10 Mathematics Solved Sample Papers
10th Sample Paper SA2 issued by CBSE (for 2015)10th Mathematics - SA2-Solved Sample Paper-K151
10th Mathematics - SA2-Solved Sample Paper-K152
10th Mathematics - SA2-Solved Sample Paper-K153
10th Mathematics - SA2-Solved Sample Paper-K154
10th Mathematics - SA2-Solved Sample Paper-K155
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CBSE Mathematics Sample Papers March 2015


10th Maths SA2 Sample paper 2015[JST101501]
10th Maths SA2 Sample paper 2015[JST101502]
10th Maths SA2 Sample paper 2015[JST101503]
10th Maths SA2 Sample paper 2015[JST101504]
10th Maths SA2 Sample paper 2015[JST101505]           Download File

Sunday, January 18, 2015

10th class solved Question paper For SA2

Xth ENGLISH COMMUNICATIVE SA_II_Question Paper [61005]

Xth ENGLISH COMMUNICATIVE SA_II_Question Paper Solution [61005]

Xth ENGLISH COMMUNICATIVE SA_II__Question Paper [2018]

Xth ENGLISH COMMUNICATIVE SA_II_Question Paper Solution [2018]

10th Sample Paper for Sanskrit Set-01

10th Sample Paper for Sanskrit Set-01[Solution]

10th Sample Paper for Sanskrit Set-02

10th Sample Paper for Sanskrit Set-02[Solution]



10th Maths Solved Sample Paper 2014 - 1

10th Maths Solved Sample Paper 2014 - 02

10th Science Solved sample guess SA-II-paper -

10th Science Solved sample guess SA-II-paper -4

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Saturday, January 17, 2015

9th Natural Resources-Questions from recent Board Exam with answer

Question: Why plants do not utilize nitrogen directly from atmosphere?

Ans. Most of the plants cannot utilise nitrogen directly from the atmosphere. They use nitrogen only when it is converted into nitrates and nitrites by the process nitrogen fixation.

Question: Name the substance that reduces the amount of dissolved oxygen in water.
Ans. Excessive growth of phytoplanktons reduces dissolved oxygen level in water

Question: Name the organisms found to be very sensitive to the levels of contaminants like sulphur dioxide in the air.
Ans. Lichens

Question: What do you understand by the term ‘Natural resources’?
Ans. Natural resources are the variety of substances that human beings get from the nature to meet their basic needs.

Question: What is strip-cropping?
Ans. Strip-cropping is the planting of crops in rows or strips to check flow of water. It is practiced in the sloping areas of hills to check soil erosion

Question: What is greenhouse effect? How is it caused?
Ans. Greenhouse effect is the progressive warming up of the earth’s surface due to the blanketing effect of man-made carbon dioxide in the atmosphere. The greenhouse gases increase the temperature of the earth's surface and lower atmosphere.

Question: Rain water sometimes contains traces of acid. Why?
Ans: Due to increase in air pollution some oxides of nitogen , sulphur, and carbon are released in air when these oxides combine with rainwater it forms nitric acid, sulphuric acid and carbonic acids respectively . These acids fall with the rain water in the form of acid rain.

Question: Define the term ‘Smog’.
Ans: Smog is a mixture of smoke or other atmospheric pollutants with fog .

Question: Water is known as ‘A Wonder Liquid’. Justify this statement by giving any two reasons
Ans : Water is known as ‘A Wonder Liquid’ because most of the chemical reaction is only possible due to water. Living organism animals, plants, microorganisms, human beings mainly contain water that makes life possible on the earth. Environment temperature, rainfall etc are maintained by water.

Question: How do forests play an important role in maintaining water cycle. 
Ans. Forests play important role in maintaining water cycle. Plants bind the soil and help in the percolation of water in the soil and thus add in water table. The water is absorbed back by roots and maximum portion of which is lost into the atmosphere in the form of vapours by transpiration. These vapours condense and form clouds. Clouds after condensation start raining. Thus plants maintain water cycle .

Question: What are aerosols ?
Ans. They are certain chemicals like fluorocarbons released in the air with force in the form of mist or vapour. Fluorocarbons, which deplete the ozone layer on the atmosphere, are emitted by jet aeroplanes in the outer space in the form of aerosols.

Question: "The flow of energy is unidirectional whereas the biogeochemical transfer is cyclic". Explain why?
Ans: A large amount of energy is always transferred from one tropic level to other.this lost of energy cannot be replenished in atmosphere. The flow of energy is unidirectional. the biogeochemical transfer is cyclic.

The biological substance cannot be lost during the biogeochemical transfer. they are only recycled. thus

Question: Justify the statement—"The nitrogen cycle is supposed to be an ideal cycle in the biosphere".

Ans: The nitrogen cycle is supposed to be an ideal cycle in the biosphere because amount of nitrogen is remain constant throughout the cycle and no nitrogen is lost. thus it follow law of conservation.

Question: The overuse of fertilizers and pesticides is harmful for the soil. Why ?
Ans: Destroys soil structure by killing soil microbes that recycle nutrients in the soil. Kills earthworms which help in making rich humus.

Question: (a) What are the two ways by which carbon dioxide is „fixed‟ in our atmosphere.(b) Which gas is produced when glucose molecule breaks down releasing energy ?
Ans: (a) the two ways by which carbon dioxide is fixed in our atmosphere are:

(i) Green plants convert CO2 into glucose in presence of sunlight

(ii) Many marine animals use carbonates dissolved in sea water to make their shells

(b) Carbon dioxide

Question: Explain in how many ways O2 is used up from the atmosphere and how it returns back to atmosphere ? 

Ans: Oxygen from the atmosphere is consumed by the humans and plants for respiration, and vehicles, factories etc.for combustion.Respiration and combustion release CO2, and this CO2 is used by the plants for photosynthesis.Plants create Oxygen with photosynthesis.

Download CBSE Summative & Formative Assignment based on CCE  Test Paper Biology Term-2 

CCE  Test Paper Biology Chapter Natural Resources ix Biology-1                        Download File
CCE  Test Paper Biology Chapter Natural Resources ix Biology-2                      
Download File
CBSE NCERT Class 9th natural resources Solved Board Questions                    
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Biology    Science  Ch-14.  Natural Resources                                                                
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Thursday, January 15, 2015

Pre board papers 2015 for class 10

10th_science_pre_board_2015-1                           Download File

10th_science_pre_board_2015-2                           Download File

10th_science_pre_board_2015-3                           Download File

10th_maths_pre_board_2015-1                             Download File

10th_maths_pre_board_2015-2                             Download File

10th_maths_pre_board_assignment_2015            Download File


CBSE Pre Board Science Question paper
CBSE 10th_mathematics_pre_board_paper
CBSE Pre Board Science Question paper
CBSE 10th_mathematics_pre_board_paper
For more paper visit 

Sunday, January 11, 2015

X and XII CBSE Date sheet for Main Examination March _2015

03rd March, 2015
10:30 AM
10th March, 2015
10:30 AM
12th March, 2015


14th March, 2015
10:30 AM
16th March, 2014
10:30 AM
19th March, 2014
10:30 AM

10:30 AM
24th March, 2015
10:30 AM

10th_cbse_datesheet_for_main_examination_2015  Download File

For sample paper visit