Thursday, November 29, 2012

CBSE _8th Some Natural Phenomenon-Lightening and Earthquack


1. How many types of charges exist?

a. One b. Three c. Two d. Four

2. Who invented the lightning conductor?
a. Alexander Fleming b. Graham Bell
c. Benjamin Franklin d. Thomas Alva Edison

3. What device is used to protect building from lightning?
a. Crescograph       b. Anemometer     c. Lightning Conductor       d. Barometer

4. What scale is used to measure the magnitude of earthquake?
a. Richter b. Celsius c. Fahrenheit d. Kilogram

5. The magnitude of earthquakes that occurred at Bhuj andKashmir were
a. less than 4            b. less than 2                    c. less than 6       d. Higher than 7

6. Name two natural phenomena which cause us heavy damage.

7. Why were the people of ancient times afraid of lightning?

8. What is lightning due to?

9. What was the discovery made by Ancient Greeks?

10. List two daily life examples where charges are produced.

11. What are charged objects?

12. How can you charge the following objects?        a. glass rod                    b. Ebonite rod

13. How can we get the following charges?                a. Positive charge         b. Negative charge

14. What is the principle of an electroscope?

15. Distinguish static electricity from electric current.

16. Like charges _________ and unlike charges____________each other.

17. What is an earthquake?

18. The weak zones where earthquakes occur are called__________ zones.

19. A lightning conductor provides a ______ ______ for the transfer of charges to the ground.

20. The magnitudes of earthquakes lesser than ___________on Richter scale does not cause severe damage.

21. What are the various causes for earth quakes?

22. Write any three harmful effects of an earthquake.

23. Name the three layers of the earth.

24. Suggest any 3 measures to protect ourselves from lightning.

25. Rearrange the steps in the formation of lightning in the form of a flow chart.
Air become charged, accumulation of charges, movements of air currents and water droplets, streaks of light and sound are produced.

Further solved questions:

VIII Physics Some Natural Phenomena Solved Questions(Notes)

8th physics Some Natural Phenomena Assignments

CBSE Class: 8th Science Chapter Earthquake solved questions

VII: Earthquake: Some Natural Phenomenon

Q. Fill in the blanks
(a) The intensity of an earthquake is measure on the -------------   ------------------
Ans: Richter scale
(b)------------- is a huge wave due to an earthquake occurring under the sea floor.
Ans: Tsunami
(c) earthquake are cause because of the motion of the ------- plates in the outer crust of the earth.
Ans: Tectonic
(d) Shock wave of earthquake are called --------------
Ans Seismic wave
(e) An earthquake of magnitude 2-4 on Richter scale is a  ---------------  one
Ans: weaker
(f) An earthquake of magnitude 8 or more on Richter scale is a  ---------------  one
Ans: stronger
(g)The instrument used to measure earthquake wave is called --------------.
Ans: seismograph
(i)The intensity of tremors is highest near the -------------
Ans: fault zone or epicenter
(j) The intensity of tremors ----------- with distance from the epicenter.
Ans: Spread
For full solved answer Visit
chemistry adda: Earthquake: Some Natural Phenomenon:CBSE Class 8th...: Q. What are tectonic plates?  
Ans: The earth's lithosphere (crust) is fragmented into many pieces of stabs or plate of rocks called tec...
Also visit
VIII Physics Some Natural Phenomena Solved Questions (Notes)

8th Science Chapter Earthquake solved questions

8th Science Chapter Earthquake:Some natural Phenomenon
Q. What is an Earthquake?

Ans: An earthquake is a sudden shaking or trembling of the earth lasting for a very short time.

Q. What Causes an Earthquake?

Ans: Earthquake is caused by a disturbance deep inside the earth’s crust created by motion of tectonic plate.

Q. What could cause a disturbance inside the earth?

Ans: Some time moving tectonic plate goes under another due to collision and cause a 
disturbance inside the earth.

Q. What are seismic waves?

Ans: Waves produce by earth quake on the surface of earth is called seismic waves.

Q. Where does the greatest number of earthquakes occur?

Ans: The boundaries of the tectonic plates are the weak zones where earthquakes are 
more likely to occur. The weak zones are also known as seismic or fault zones.

Q. What are different cases of tremors?

Ans: Tremors on the earth can be caused when a volcano erupts, or a meteor hits the earth, or an underground nuclear explosion is carried out. However, most earthquakes are caused by the movement of earth’s tectonic plates.

Q. What is the scale used to measure magnitude of the intensity of earthquake?

Ans: Richter scale

Q. What is the instrument used to measure seismic wave?

Ans: Seismograph.

The instrument is simply a vibrating rod, or a pendulum, which starts vibrating when tremors occur. A pen is attached to the vibrating system. The pen records the seismic waves on a paper which moves under it. By studying these waves, scientists can construct a complete map of the earthquake

Q.Define: hypocenter, epicenter, Seismic waves

Ans: The place below earth surface from where the earthquake originates is called the hypocenter or the focus of an earthquake. It is often several kilometers below the earth’s surface. 

The spot on the earth’s surface exactly above the hypocenter of an earthquake is  the epicenter.

The collision of plates gives rise to vibration of earth surface called Seismic waves this through the earth.

Q. What safety measured you taken during an earthquake If you are traveling in a motor vehicle?

Ans: Drive slowly and do not come out till the tremors stop.

Q. What safety measured you taken during an earthquake If you are inside house?

Ans: Take shelter under a table and protect your head by wrapping your arms around it and curling into a ball

Sunday, November 25, 2012

Activity based Questions with answer: X Chapter: Carbon and Its Compounds

Activity based Questions with answer: X Chapter: Carbon and Its Compounds

1. Q. What happen when few drops of alkaline KmNO4 added to Ethanol?

Ans: In the begging color of KmNO4 disappear. When excess KmNO4 is dissolved in solution colour cannot disappear because whole Ethanol gets oxidized into Ethanoic acid.

CH3CH2OH ----- KmNO4------Heat------->CH3COOH

Hence, alkaline KmNO4or Acidified K2Cr2O7 oxidized alcohol into ethanoic acid

2. Q. How can we convert unsaturated hydrocarbon into saturated hydrocarbon?

Ans: By the addition reaction of unsaturated hydrocarbon with halo atom in the presence of catalyst.

HC=CH    +H2 -------------Ni--------5700 K------> Ch3-CH3

R2C=CR2 + H2    ------------Ni---------> R2HC-CHR2 (Vegetable Gee)

This reaction is known as Hydrogenation reaction.

3. Q. How can you test that given hydrocarbon is unsaturated?

Ans: When few drops of Bromine is added to unsaturated hydrocarbon its colour disappear due to addition reaction.

For example: If drops of bromine water added to ethyne, the colour of Bromine disappear due to addition reaction. HCCH + Br2     -------------> HBr2 C – CHBr2 (Tetra room ethane is formed)

4. Q. How can you prepare alkenes from Ethanol?

Ans: When Ethanol heated in presence of Conc.H2SO4 or Al2O3 at 6230C ,Ethanol loose water molecules and form alkenes. C2H5OH ---H2SO4------6230C------>CH2=CH2    + H2O

5. Q. What happen when a piece of sodium metal added to Ethanol?

Ans: Sodium ethoxide is formed with evolution of H2 gas

C2H5OH         + Na -------------> C2H5ONa    + H2

6. Q. What happens when few drops of Conc.H2SO4 is added to Solution of Ethanoic acid and Ethanol?

Ans: A substance with fruity smell is formed called Ester.This reaction is known as Esterification

C2H5OH + CH3COOH ------H2SO4------> CH3COO C2H5 (Ester or, Ethyl Ethanoate)

7. Q. What types of flame produce by burning of Benzene, Nepthline and Camphor?

Ans: Smoky flame due presence of excess carbon content.

8. Q. What is Gasol?

Ans: The mixture of petrol with alcohol up to 20% is known gasol.

9.Q. Why Acetic acid is called glacier acid?

Ans: Acetic acid freezes at 290K in cold weather and form crystals.This is why acetic acid is called glacier acid.

10. Q. What is saponification?

Ans: When sodium hydroxide react with ester and form alcohol and sodium Ethanoate. This reaction is used to form soap So this reaction is known as saponification.

CH3COO C2H5     +     NaOH  ------------>  CH3COONa   + C2H5OH
For further reading Visit 
Links For   CBSE Class X Science Term-II
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Friday, November 23, 2012

7th Reproduction in plants solved Questions,

7th Reproduction in plants solved Questions,MCQ,For Summative assessments

1.What is meant by reproduction?

Ans: The process of producing new individuals of same kind of the same species is called reproduction.

2. Why reproduction is a essential life process?

Ans: Reproduction is essential for continuation of the species from generation to generation.

3. What are the different modes of unisexual reproduction?

Ans: modes of reproduction evolve only one parent is called unisexual reproduction.
(a) Fission: The mode of reproduction in which unicellular organism split into two equal halves and produce new ones is called binary fission. For example amoeba and bacteria
(b) Fragmentation: The mode of reproduction in which body of plant breaks up into smaller fragments and each fragment grows into a new individual is known as Fragmentation e.g. Spirogyra , algae
(c) Budding: The mode of reproduction in which small buds when develop get separated and mature into new organisms is called Budding. E.g. Yeast, Hydra, Bryophyllum
(d) Spore formation: The mode of reproduction takes place by means of spores is called spore algae and fungi
The spores are covered by thick walls that protect them until they come into  contact with another moist surface and can begin to grow.

4. Mention some of the spores of asexual reproduction.

Ans:  Aplanospores, Zoospores, Akinetes and Conidia

5. What do you mean by vegetative propagation?

Ans:  Vegetative propagation is the ability of plants to reproduce by using vegetative parts like root ,stem and leaves is called vegetative propagation.

6.  Why there are so many methods of reproduction?

Ans:  It is due to complexity of the body design of organisms.

7.What is sexual reproduction?

Ans:  Sexual reproduction is the process in which two components ( male and female) are involved to produce offspring of their own kind.

8. Name the reproductive organ of a flowering plant

Ans: The flower is a reproductive organ of a flowering plant

9. Name the male and female part of flower.

Androecium is the male part of a flower,and Gynoecium is the female part.

Androecium is a group of stamens. Each Stamen consists of a stalk called the filament and a small bag like structure called the anther at the tip. The pollen grains are contained in the anther within the pollen sacs

Gynoceium is the female part of the flower and consists of the carpels or ovary. 

Gynoceium has three parts 
1) Stigma 
2) Style and 
3) Ovary. 
The ovary contains the ovules and each ovule carries within it an embryo sac, within which lies the egg cell or the female gamete.

10.How does sexual reproduction take place in flowering plants?

Ans:  The sexual reproduction in flowering plants involves
1. Pollination 2. Fertilization
Transfer of pollen grains from the anther to the stigma is called pollination.
Pollen grains are transferred mainly by wind, water and insects. They are called as pollinating agents.
The fusion of a male gamete with egg is known as fertilization. The fertilized egg is known as zygote which develops into embryo.

11.Why are there so many varieties of fruits?

Fruits develop by many ways so there are many varieties of fruits. For example, some fruits develop without the act of fertilization. Such fruits are called arthenocarpic fruits. E.g. seedless grapes, guava, mango etc.

12.Explain different parts of flower?

Ans: Following are the parts of flowers:
a)Sepal: Green leafy part of flower that protect flower in bud condition.
b) Petal: Coloured leafy part of flower that attract insect for pollination
c) Stamen: The male parts of flower that contain pollen grain
d)pistil: The female parts of flower that contain ovary at bottom
what are the various methods of vegetative propagation?

13.Explain three artificial  methods of Vegetative Propagation

Ans:  Cutting: Here the cuttings of the "parent" plant are removed and placed in a suitable environment so that they can grow into a whole new plant. For example rose cutting.
Layering: The stem is bent down and the target region buried in the soil. The buried part of stem develops roots and is detached from the plant and develops into new plant.
Grafting: In grafting a shoot or bud of a selected, desired plant (scion) is grafted onto the stock of another type of plant.
Plant tissue culture: Tissue culture is the artificial method of reproduction where a small cutting of plant such as root or stem is taken and is grown in laboratory condition by providing it with suitable nutrients in a media and growing them in a petri plate or test tubes. The plant is provided with the most hygienic condition.

14. What are the various methods of vegetative propagation?

  • Vegetative Propagation by Roots- Eg. Dalbergia sissoo (Shishan) 
  • Vegetative Propagaton by Stem- Eg. Banana
  • Vegetative Propagation by Leaf- Eg. Bryophyllum.
  • Cutting- Eg. Sugarcane
  • Grafting- Eg. Desi Mango
  • Budding- Eg. Rose
  • Layering- Eg. Jasmine
  • Micropropagation or Tissue Culture- Eg. Dahlia
15.What are the advantages of vegetative reproduction?

Ans:  a) It allows them to produce new plants quickly without any reproductive organs.
b) The plants produced by this method are exact copies of the parent plant
c) New varieties of plants having required characteristics can be developed by this method.

16.How is zygote formed in plants?

Ans:  When male gamete present in pollen grain moves into ovules and fuse with female egg cell inside ovules and zygote is formed .This process is called fertilization.

17.What are the different types of pollination found in flowering plants?

Ans: Pollination is of two types. They are
1. Self pollination: The transfer of pollen grains from the anther of a flower to the stigma of the same flower or another flower of the same plant is known as self pollination or autogamy.
2. Cross pollination: The transfer of pollen grains of a flower to the stigma of another flower of a different plant of the same species is called cross pollination or allogamy

18. What is the roll of pollen grains in flowering plants?

Ans: Male gametes are produced inside pollen grains.

19.How does fertilization occur in flower?

Ans:  After pollination pollen grain germinate on the stigma and moves through style to reach into ovules and fuse with female gamete. Thus fertilization occur.
Where and how are seeds formed in plants?
In side ovary, the ovule develops into seed. As seed form, the ovary increases in size and became fruit.

20. Name two kinds of gametes in flower?

Ans: Pollen grain and egg cell

21. What are pollen grains

Ans: Male reproductive cell

22.What is found in embryo sac

Ans: Female reproductive egg cell

23. Name the plant form colonies by budding?

Ans: Duckweed or hydra

24. Why are spore formed?

Ans: Spores are formed to help over coming unfavorable condition for reproduction

25. How is Bryophyllum plants propagated?

Ans: By leaves

26. How does spirogyra reproduce?

Ans: Fragmentation

27. What is grafting ?

Ans : Grafting is a method of vegetative propagation in which two parts of two different plants are joined together in a specific manner so that they unite to grow as one plant.

28.What is 'scion' ?

Ans : The portion of the plant which is grafted on other plant is called scion.

29.What is 'stock' ?

Ans : The plant on which grafting is performed is called stock.

30.Fill in the blanks

(a) Pollination by animals and birds is known as --------------

Ans: Zoophily.

(b) Pollination by birds is called ----------------

Ans: Ornithophily

(c) The egg cell or the female gamete lies within ----------------

Ans: embryo sac

(d) Flowers pollinated by wind are called -----------------

Ans: Anemophilous

(e) The Pollination by Water is known as ----------------------


For further study visit post related to Reproduction in plants

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Friday, November 16, 2012

CBSE 7th Grade Chapter 17- Forest – Our Life Line

Answer these question

1. Question:  Explain how animals dwelling in the forest help it grow and regenerate.

Ans: Animals in the forest help it grow and regenerate in many ways like: Animals help in dispersal of sees. Micro organism supply nutrients for growth.  Many seedlings growing in a decaying heap on animal droppings.

2. Explain how forests prevent floods.

Ans: Forest absorb rainwater and allows it to seep naturally.its leaves and branches prevent rain to hit the ground directly.

3. What are decomposers? Name any two of them. What do they do in the forest?

Ans: The micro-organisms which convert the dead plants and animals to humus are known as decomposers like Fungi and bacteria. They  convert dead leaves and dead animals  into humus

4. Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.

Ans: During respiration plants and animals take in oxygen  and release carbon dioxde. During  photosynthesis plants take in carbon dioxide and release oxygen. So plants help to maintain the oxygen and carbon dioxide balance in the atmosphere. This is why forests are called green lungs.

5. Explain why there is no waste in a forest.

There are several organisms and micro-organisms that live in the soil convert waste into usefull nutrients called humus. This is why there is no waste in forest.

6. List five products we get from forests?

Ans: We get several useful products from forests like wood, spices, gum, oils, honey, sealing wax, catechu, fodder for animals, medicinal plants etc.

7. What are the importances of forests?

Ans: Forests provide us with oxygen. They protect soil and provide habitat to a large number of animals. Forests help in bringing good rainfall in neighboring areas. They are a source of medicinal plants, timber and many other useful products.

8. What would happen if forests disappear?
Why should we worry about the conditions and issues related to forests far from us?

Ans: the conditions and issues we have to face when  forests disappears are
 (a)Soil erosion: Trees in a forest hold soil with their roots. If trees are gone, soil will be washed away.
(b) Land slides: Without trees, land will be very unstable and easily down the slope
(c) Water pollution: Without tree roots holding the soil  in a forest, soil will run into the river.
(d) Temperature increase
(e) Loss of biodiversity: Plants and animals will lose their food and shelter
(f) Floods: Bald hills and mountains can no longer hold back sudden flows of water, which cause
(g) Increase in carbon dioxide: Depletion of forests results in increase in carbon dioxide, which will cause global warming.

9. Explain why there is a need of variety of animals and plants in a forest?

Ans: Animals and plants in a forest are dependent on the other for food. So there is a need of variety of animals and plants in a forest. Many food chains can be found in the forest like Grass→ insects→ frog→ snake→ eagle.

10.Fill in the blank:

(a) The insects, butterflies, honeybees and birds help flowering plants in ------.
(b) A forest is a purifier of ------------  and -----------------.
Air, Water
(c) Herbs form the ----------------- layer in the forest.
(d) The decaying leaves and animal droppings in a forest enrich -----------.
Soil(Fertility the Soil)

Continue learning : Chapter-17-Forest –Our Life Line