Questions & Answer - 2020

• Why does chopping an onion make you cry?

Ans. The tears that flow from the eyes while chopping onions are due to a chemical reaction that takes place in the eyes. They are not emotional  tears. 

        The onion plant absorbs sulfur from the soil. This sulfur helps to form a substance called amino acid sulfoxides. When we cut an onion, the cells of the onion are broken, and these chemicals are released in the form of vapor.

      There are glands in the eyes, called lachrymal glands, which produce tears. These glands become irritated and produce tears. The chemical vapors from the onion reacts with the water in our tears to form mild sulfuric acid. The sulfuric acid burns, stimulating the eyes to release more tears.

• What happens when it rains in your surroundings?

Ans. When it rains in my surroundings, the trees sway and begin to look clean and fresh. There is the pitter-patter sound of the rain on the roofs of all the houses. Very soon, streams of water begin to flow along the road. We begin to hear the croaking of the frogs. Everybody comes out to watch and enjoy the rains.

• How is a glacier like a cheese grater ?

Ans . Glaciers are like rivers of ice that slowly move over land. Glaciers carve out pieces of ground just as the sharp edges of a cheese grater break off bits of cheese. The biggest glaciers are found in Antarctica and Greenland.

• Do earthquakes hit the same places ? 

Ans. Beneath the ground, the Earth's rocky crust is broken up into large pieces called tectonic plates. These plates constantly move and can rub against each other, pull apart ,, or collide, causing earthquakes. 

• How do raindrops make a cave ?

Ans. When it rains, some of the carbon dioxide gas in the air dissolves in the raindrops. This makes the water slightly acidic . When the rain meets certain rocks, such as limestone, the water eats away at them, making a hole. These holes grow and become caves. 

• Does land stay still ?

Ans.  The Earth's surface is always moving but usually so slowly that we can't feel it. In the past, this motion caused the continents to collide, forming a supercontinent called Pangaea. The continents may collide again, many millions of years in the future.

• How did the Earth form ?

Ans. The Earth was once space dust. The sun came into existence about 4.6 billion years ago. It pulled gas, ice, and rocks into circles around it called orbits. This spinning rubble collided to form the planets in our solar system, including the Earth.

• What is the universe made of ?

Ans. Four per cent baryonic matter, 23 per cent dark matter, and 73 per cent dark energy! Baryonic matter, that is, protons, neutrons and electrons, make everything in the universe , including the planets, stars and our Earth. Dark matter has an effect on stars and planets but we cannot see it. Dark energy is the opposite of gravity, it pushes everything away, thus expanding the universe.

• What is the Big Bang?

Ans.  A theory that explains the birth of the universe. The Big Bang theory explains that our universe exploded about 14 - billion - years ago. This explosion produced matter and energy. At that time, it was dense and extremely hot. The universe grew and temperatures cooled down, and eventually galaxies, stars and other heavenly bodies were formed.

Fact  👉 Our nearest neighbor in space, Proxima Centauri is 4.3 light years away, which is about a hundred million times farther than a trip to Earth's moon. To reach it by spaceship would take at least 25, 000 years !

• What did the stag like about himself? Why?

Ans. The stag liked his beautiful, curving antlers. that they looked graceful and added to his beauty.

• How did Gandhiji win the war of India's independence and how do other leaders win wars?

Ans. Gandhiji won the war of India's independence without using any arms or weapons. Others leaders win wars by hurting others and killing them.

• What did Gandhiji give a lot of importance to?
• Ans. Gandhiji gave a lot of importance to truth, simplicity and non-violence.

• How did Gandhiji dress?
• Ans. Gandhiji dressed very simply. He wore just a loincloth, and sometimes a shawl.

• Why were women not seen at public meetings in Odisha?
• Ans. Women were not seen at public meetings in Odisha because they were so poor that they did not have anything decent to wear.

• What did Gandhiji finally wear for the reception ?
• Ans. Gandhiji wore a simple loincloth and a shawl for the reception.

• What was the path that Gandhiji showed the people?

Ans. Gandhiji showed the people the new path of satyagraha.

• How will you use an 'online' dictionary?

Ans. We just type the word we want to look up and the computer instantly gives us the meaning, use, pronunciation, etc. of the word.

• What is land made up of?

Ans. Land is made up of soil, rocks, stone, etc.

• What do you see on this land?  

Ans. Mountains, valleys, rivers, oceans can be seen on the land. In the urban region we can see buildings and other constructions, bridges, roads, etc. In rural areas we can see farms and orchards and some tree cover.

• Why is there a shortage of water even though it occupies about 71% of the earth's surface? 

Ans. 1) Though 71% of the earth's surface is covered with the water, most of this water is not usable and potable.  2) 97% of this water is salty water of the sea. This water cannot be used for agriculture or for drinking. cooking, etc. 3) Some fresh water is in frozen state. 4) Due to tremendous increase in the population the demand for water is also rising.  5) Due to global warming there are droughts and this results in lack of water. 6) Due to all these reason there is always a water shortage even though the 71% of earth's surface is occupied by water.

• What are the various constituents of air?

Ans. I. Different constituents of the air :

1) Gases such as nitrogen, oxygen, carbon dioxide, nitrogen dioxide, sulfur dioxide.

2) Inert gases such as argon, helium, neon, krypton and xenon.

3) Other inclusions such as water vapor, smoke, fog, smog, soot, etc.

II.  Uses of the constituents of air :

1) Nitrogen : Nitrogen helps in building up proteins in the living organisms. It is also used in the production of ammonia and also in the airtight packaging of the foodstuffs. 

2) Oxygen : Oxygen is essential for respiration and also for combustion of all the substances.

3) Carbon dioxide : Plants need carbon dioxide to perform photosynthesis. It is also used in fire extinguishers.

4) Argon : Argon is used in the electric bulbs.

5) Helium : Helium is used for obtaining low temperature and also for generating lift in airships.

6) Neon : Neon is used in decorative lights used for advertisements and also for street lighting.

7) Krypton : Krypton is used in fluorescent tubes.     

8) Xenon : Xenon is used in flash photography.

• [ Short note ]  on 'Air pollution.'?  

Ans. Air pollution is an undesirable change in the quality of the air. Vehicles and the industrial processes are two main sources of air pollution in both there is incomplete combustion of fossil fuels. These exhaust gases are carbon dioxide, carbon monoxide. sulfur dioxide, nitrogen dioxide which are very harmful. Smoke fog and soot are also hazardous air pollutants. Due to air pollution there is environmental degradation and threat to the human health.

• Which layers are seen in land ? Explain it in brief.?

Ans. 1) The uppermost layer of the soil is formed by the decomposition of dead animals and plant matter. This is called humus.

2) Below the humus is a layer of immature soil which is full of sand soil, small stones, worms, and insects.

3) Under this layer there is a layer of soil and bedrock. 

4) The bedrock has minerals in it. The color and texture of the soil depends upon type of bedrock in a particular region.

• What are the constituents of soil? Classify them as biotic and abiotic constituents.?

Ans. 1) The particles of soil, sand, rocks and stones, etc. are the abiotic constituents of soil.

2) The biotic constituents are microbes, bacteria, unicellular protozoans. fungi, algae, small insects like ants and termites, worms, centipedes and millipedes, earth- worms , etc.

• What would have happened if there were no air on the earth?

Ans. If there is no air on the earth, the life will come to an end. Because of water of  oxygen, all the living organisms will die of suffocation. If air is not there, there will be no atmosphere. So there will not be gravitational force, air pressure, etc. All the harmful radiations from the outer space will then reach till the earth's surface. Only anaerobic microbes which do not need oxygen for their survival, will subsist on the earth.

What will happen if .........:

1) Microbes in the soil get destroyed.

Ans. The decomposition process in the soil is done by the microbes. The weathering of rocks is also done to some extent by the microbes. If all the microbes in the soil are destroyed the processes of decomposition and weathering would not take place. The humus will not be formed. Due to lack of decomposition process, the dead and decaying matter will remain scattered everywhere on the earth.

2) The number of vehicles and factories in your surroundings increases.

Ans. In vehicles as well as factories there is continuous combustion processes occurring. Particularly in vehicles there is incomplete combustion of the fossil fuels releasing many air polluting gases in the atmosphere. Polluting gases like carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen dioxide, etc. will cause dangerous and harmful effects on the surrounding environment and human beings. Industries will also throw toxic gases and effluents into the surrounding. If the number of vehicles and factories in our surroundings increases then it will be hazardous for the environment and health of the entire living world.

3) The total supply of potable water is finished.

Ans. If the total supply of potable water is finished, the the living world will also come to an end.

• What are the similarities between plants and animals?

Ans. Plants and animals are both living things. Most of the characteristics of living things are seen in both of them. Growth. respiration, excretion, responsiveness to stimuli and reproduction are the common characteristics in both of them. Plant body is also made up of cells just like that of the animals body. Thus, both have cellular structure. Animals and Plants both need water and nutrients for survival.

• What is the main difference between the movements of plants and animals?

Ans. Plants show responsiveness towards stimuli. But they cannot change their place. Blooming of the flower, closing of the leaflets, turning towards sunlight are the movements shown by the plants, whereas animals can change their place on their own will and can move of their own accord. 

• What are the differences in the body structure of animals like a snake, a lizard, a tiger, a fish, an eagle, a hen, a crab, a housefly, an earthworm, a crocodile and a grasshopper?

Ans. Out of all the above animals, tiger is a mammal. It has head, neck, torso, tail and two pairs of limbs for locomotion. Snake, lizard and crocodile are reptiles. Snake has limbless body. Lizard and crocodile have smaller limbs in comparison to their bulky bodies. There is no prominent distinction between head and torsion as there is no distinct neck present in these animals. Fish is completely aquatic animals . It has a streamlined body covered with scales. It swims with the help of fins and breathes with gills. An eagle and a hen are birds. Their body is covered with feathers. Both have wings, but eagle can fly at great heights due to its powerful wings. Hens cannot fly to heights and is usually seen packing at the ground level. An Earthworm has segmented body which is slippery and tapering. There is no distinct head, torsion or limbs in such invertebrate animal. It does not even have a vertebral column. Housefly and grasshopper are both insects. Both of them have six pairs of walking legs. The hind legs of grasshopper are very strong and thus it can jump to a longer distance. Housefly has delicate wings and thus keeps on hovering over a small area. In both of these insects, there is head, thorax and abdomen. Crab's body is covered with a thick and hard carapace or shell. Crab has five pairs of walking legs. The first pair of these legs is modified to form pincer or chela which is used for capturing a prey. This animal is seen in the coastal part of the seas or banks of rivers. The structure of the body is very different in it. 

• What is the chain of bones in the center of our body called ?

Ans. The chain of bones in the center of our body is called a vertebral column.

• What type of plants are toadstools and mushrooms ?

Ans. Toadstools and mushrooms are examples of fungi. According to old system of classification. fungi were included under kingdom Plantae or Kingdom of plants. But Since they are not autotrophic, they cannot be included under plants. They are decomposers and hence have saprotrophic mode of nutrition.

• Why is the stem of the cactus fleshy ?

Ans. Cactus is a desert plant. In order to survive in a desert, its body is highly modified The leaves of cactus are reduced and converted into thorns. Therefore, stem takes up  the function of photosynthesis. It thus turns green and fleshy.

• What different criteria are used to classify plants ?

Ans. There are four different criteria used to classify plants :

1) The shape and height of the stem : According to this criteria plants are classified as trees, shrubs, herbs and creepers.

2) The lifecycle of the plants : According to this criteria plants are classified as annual, biennial and perennial.

3) Whether the plant bears flowers or they do not bear : According to this criteria plants are classified as flowering plants and non-flowering plants.

4) The habitat of plant : According to this criteria, plants can be classified into land, desert, water, marshy area plants.

• What are the types of disasters ? 

Ans. Disasters are of two kinds, viz. natural disasters and man-made disasters.

• Why are the electric boards fitted on the wall made of plastic or wood ? 

Ans. In the plastic and wooden material there is no electrical conductivity. When we are touching electric boards we should not get electric shock. Therefore, the electric boards fitted on the wall are made of plastic or wood.

• The handle of pressure cooker is made of plastic. Why ?

Ans. Pressure Cooker is made from mixed metals such as Hindalium or aluminum. When it is on cooking fire, it becomes hot. If we life it up in a hurry, we may get burnt. To avoid this the handle of cooker is made from plastic. Plastic is not thermal conductive material. Therefore, we many not feel the heat of the cooker while lifting it up.

• What is it made from ? Why ?

1) A sickle to cut sugarcane :

Ans. The sickles used for cutting sugarcane are made from iron or other strong metals. Hardness, malleability, and ductility are the characteristics of iron. Therefore it is ideal to use it in making of sickle. For cutting the sugarcane we need a strong equipment.

2) The sheets used for roofing :

Ans. The sheets used for roofline houses are made from aluminum. Aluminum is a metal that is light in weight and is durable and rust free. It can protect the house well from rains and sun.

3) A pair of tongs : 

Ans. In olden times, a pair of tongs were made from iron, but now they are made from stainless steel, which is durable, strong and rust free. Usually in a kitchen this equipment is used and hence it is made from high quality metals.

4) Electric cables :

Ans. Electric cables are either of copper or aluminum. Copper is a good conductor of electricity. Therefore, most of the electric cables are made from copper.

5) Ornaments :

Ans. Ornaments are made from gold or silver. Nowadays platinum is also used for making ornaments. All these metals have characteristic of ductility. Hence they can be stretched and pulled in the form of wires. Making ornaments from these metals thus becomes easier. Diamonds are also studded in ornaments. Diamond is the hardest substance and has shine. Gold and silver have luster which makes ornaments shine.

• Why does this happen? 

Coconut oil thickens in winter .

Ans. In winter, the temperature of air is less. At this temperature the freezing poing of coconut oil is reached. Therefore it freezes and appears to be thickened.

• What will happen if ......? And why ?

1) Nails are made of plastic.

Ans. Nails should be made from metals that have characteristic of hardness. Plastic is a brittle substance. It cannot withstand hammering. neither it can enter the material in which we may try to pierce them. Therefore nails made of plastic cannot be used.

2) A bell is made of wood.

Ans. Sonority is the characteristic of metals. The sound produced by metal bell would be melodious. Similar. Sound cannot be produced by wooden bell as wood does not have characteristic of sonority. 

3) A knife is made of wood.

And. The wood is not metal and is thus not hard. The work of knife cannot be performed by the wooden knife. It cannot cut the objects due to lack of hardness.

4)An axe is made of rubber.

Ans. Rubber is a substance having elasticity. The rubber axe will rebound when hit upon an object. The metal axe can perform a function as the metals are hard substances. The rubber axe will not be able to do this function.

• What type of plants are toadstools and mushrooms ?

Ans. Toadstools and mushrooms are examples of fungi. According to old system of classification, fungi were included under kingdom Plantae or kingdom of plants. But since they are not autotrophic, they cannot be included under plants. They are decomposers and hence have saprotrophic mode of nutrition. 

• Why is the stem of the cactus fleshy?

Ans. Cactus is a desert plant. In order to survive in a desert, its body is highly modified. The leaves of cactus are reduced and converted into thorns. Therefore, stem takes up the function of photosynthesis. It thus turns green and fleshy.

• What is meant by disasters ?

Ans. A sudden event causing large scale damage to life, property and social aspects of our nation or society is called a disaster.

• What is vulcanization ?

Ans. vulcanization is a chemical process, In this process. the rubber is heated with sulfur for three to four hours. This process makes rubber hard.

• We must use cotton clothes in summer.

Ans. Cotton clothes are made from natural fiber. The sweat is absorbed in these fiber. The skin remains dry and the chance of catching skin infection is less. By using clothes made from synthetic fiber, we may feel uncomfortable. Therefore, we must use cotton clothes in summer. fiber

• We must observe economy in the use of materials.

Ans. Man has over used natural resources to satisfy his needs. He also made many new substances by changing the natural substances in an irreversible way, While making such substances, the properties of the constituents undergo change due to chemical reactions. We cannot obtain the natural resource again. Many a times these man-made substances are hazardous for the environment. e.g. thermocol , plastic. In order to save our natural resources and prevent its depletion, we must observe economy in the use of them.

• Man-made material has more demand.

Ans. Man-made material is easy to use, low in cost, available in plenty . The original natural materials are changed into man-made material to suit our convenience. e. g . instead of cotton and wool fiber, synthetic fiber are more convenient for use. Plastic and thermocol are the materials that has fast replaced the natural alternatives. Thus man-made material has more demand. 

• Humus is a natural material.

Ans. There are soil microbes that bring about decomposition process in the soil. Form the dead and decaying remains of animals and plants humus is formed by them. This is a natural process and therefore humus is called a natural material.

• Where was the process of making paper invented ? 

Ans. The making of paper was invented in china. In India, writing was done on bhojpatra much before paper was discovered. In China,  paper was manufactured in 100 B.C. 

• What kind of paper is used for our textbooks ? What size is it ?

Ans. Our textbooks are made of paper called Creamware. Its size is A4 and thickness 70 GSM.

• How is paper for currency notes manufactured ?

Ans. In our nation, the currency notes are made from cotton pulp, stems of balsam and special kinds of dyes. Some currency notes are made of starchy paper and fibers of clothing. The layer of gelatin is applied on the currency notes. Therefore they remain crisp and straight.

• What is the use of food for living things ?

Ans. Food is needed for all the living beings for the following purposes :

1) Obtaining energy 2) For the growth of the body 3) To carry out day to day functions of the body  4) To develop resistance against diseases. 

• What are the five layers of the atmosphere ?

Ans. The troposphere, stratosphere, mesosphere, ionosphere and exosphere are the five layers of the atmosphere.

• Uses of constituents gases in the air : [ Gases / Uses ]

Nitrogen : Building up proteins in living beings, Production of ammonia, Airtight packaging of food stuffs.

Oxygen : Respiration and combustion.

Carbon dioxide  : Photosynthesis in plants, in fire extinguishers.

Argon : In electric bulbs.

Helium : Obtaining low temperatures and generating lift in airships.

Neon : Decorative lights and street lighting.

Krypton : Fluorescent tubes.

Xenon : Flash photography .

• What is land made up of ?

Ans. Land is made up of soil, rocks, stone, etc.

• What do you see on this land ?

Ans. Mountains, valleys, rivers, oceans can be seen on the land, In the urban region we can see buildings and other constructions, bridges, roads, etc. In rural areas we can see farms and orchards and some tree cover.

• What has man created on land ?

Ans. Man has created different types of shelters, roads for transport and agricultural farms on the land.

• Is land flat everywhere ?

Ans. No, land is uneven. At some places there are mountains and hills while at some places there are valleys. 

• How much is the proportion of the gases in the stratosphere ?

Ans. The proportion of gases is about 19% in the stratosphere.

• Why is water called a universal solvent ?

Ans. Many substances readily dissolve in the water, therefore water is called a universal solvent.

• How is water formed ?

Ans. If hydrogen gas burns in the air, it combines with oxygen and this forms water.

• Which useful substances are obtained from crude oil ?

Ans. Fuels such as petrol, diesel, kerosene, paraffin and other useful substances such as wax and tar are obtained from crude oil.

• Why are air, Water and land considered to be valuable natural resources ?

Ans. Air, water and land are the factors essential for sustaining living world on the earth. All the essential things required for the survival are obtained through air, water or land. Since by fulfilling the needs of living organisms, they help in survival of all living organisms, therefore, air, water and land are considered to be valuable natural resources.

• Is all the food we eat used by the body?

Ans. All the food that we eat is not used by the body. Some part which is not essential and some which is not digested is thrown out of the body.

• What is the unused part of food converted into ?

Ans. The unused food is converted into excreta or farces.

• Light flashed suddenly into your eyes? 

Ans. The eyes are immediately shut or we may instantly blink.

• Suddenly you felt a pinprick?

Ans. We feel  intense pain and thus we instantly withdraw our hand.

• The leaves of the mimosa plant were touched.

Ans. The leaves of mimosa plants are folded at once upon touching. 

• At sunset, lamps on the street or courtyard are lit and insects gather around the lamps?

Ans. If the lamps are switched off the insects go away, however, if the lamps are switched on they are attracted towards the light and are seen flocking near the lamp.

• What helps them to breathe ?

Ans. 

1) A fish - gills  2) A snake - lungs  3) A crane - lungs aided with air sacs. 4) An earthworm - skin ( cuticle ) 5) Man - lungs, diaphragm helps in breathing. 6) A banyan tree - tiny pores on the leaves.  7)  A caterpillar -  spiracles.

• What are the similarity between plants and animals ?

Ans. Plants and animals are both living things. Most of the characteristics of living things are seen in both of them Growth, respiration, excretion, responsiveness to stimuli and reproduction are the common characteristics in both of them. Plant body is also made up of cells just like that of the animals body. Thus, both have cellular structure Animals and plants both need water and nutrients for survival. 

• How is the plant kingdom useful to us ?

Ans. We use plant materials in most of our daily routine. Plants provide us with food in the form of grains, fruits, vegetables, etc. Some plants like vasaka, Hirda, Behada, Asparagus are of medicinal importance which we use as home remedies for minor illnesses. Some plants are used for industrial purposes. Plants provide us with timber and wood which are used in making furniture and houses. Plants like cotton and jute provide us with fiber. In this way all the basic needs of man. i.e. food, shelter and clothing are fulfilled by plants.

• How is the animal kingdom useful to us ?

Ans. Domesticated animals are useful to us in many ways. Animals provide us with food in the form of milk, meat, eggs, etc. The occupations like poultry, dairy, fishery are dependent on animals. Animals like oxen, horse and camel are used for transportation. Earthworm helps in decomposition of wastes and makes the soil fertile. It is thus a friend of the farmers. Some insects like honey bees, lac insect, silk moth are useful to mankind.

• What makes living things different from non-living things ?

Ans. In living things we can see growth, feeding, respiration, excretion, responsiveness to stimuli, movement and repoductio Living beings also show death, All such characteristics are not seen in non-living things . This meld the difference between living and non-living things.

• What differences do you see in the growth of trees like the mango, banyan and peepal and that of bamboo, coconut and toddy plants ?

Ans. During growth of mango, banyan and peepal many branches and sub-branches are given out. This increases their canopy. Bamboo. coconut and toddy plants do not develop branches. They grow tall without branching.

• What is the sticky substance seen in the stems of the babul ( Acacia ) or drumstick trees ?

Ans. Sticky substance seen in the stems of the babul  (Acacia ) or drumstick trees is waste product of the tree. Since it is unwanted substance for the plant it is secreted out through the bark of the tree.

• What is the main difference between the movements of plants and animals ?

Ans. plants show responsiveness towards stimuli. But they cannot change their place. Blooming of the flower, closing of the leaflets, turning towards sunlight are the movements shows by the plants, whereas animals can change their place on their own will and can move of their own accord.

• In which spheres of the earth do living things exist ?

Ans. Living things exist in all the three spheres of the earth, i.e. hydrosphere, lithosphere and atmosphere.

• Are the plants and animals that you have seen all alike ?

Ans. No, the plants and animals are of great variety. There is diversity in shape, body structure, color types, etc, among the different animals and plants.

• What are the similarities between a mango, a banyan and a tamarind tree?

Ans. Mango, banyan and tamarind are huge trees.

• What are the similarities between the hibiscus, oleander and lantana plants ?

Ans. These plants are shrubs that do not grow tall.

• What are the similarities between the fenugreek and periwinkle plants?

Ans. Fenugreek and periwinkle are small herbs.

• Where does the lotus grow ?

Ans. Lotus is an aquatic plant and it is seen submerged in the water. Its roots are under water while leaves float on the water surface.

• Where does the dodder plant grow ?

Ans. The dodder plant is a parasitic plant. It is seen growing on a host plant. It  can absorb all required nutrients from the host plant.

• Dog bite ?

Ans. The wound caused by the dog bite should be washed with soap and clean, germ free water. It should be rinsed with solution of potassium permanganate. The wound should be covered with a dry cloth and victim should be taken to doctor for dressing of the wound. Injection of anti-rabies should be given to the victim.

• Scratches / Bleeding ?

Ans. The very first thing to be done in case of bleeding is to stop it. Make the person sit or lie down comfortably. The bleeding part should be cleaned with germfree water and it should be kept above the level of the heart. Apply antiseptic cream to the wound. If the wound is deep rush to the doctor to stitch it and get proper medical care.

• Burns / Scalds ?

Ans. First of all, the extent and severity of burning should be seen. If there is a minor burn, immerse the burnt part in cold water. Give cold water to the victim. Clean the wound with germ free water and antiseptic solution. Oily ointments should not be applied. If there are serious burns, give emotional support to the victim and seek medical treatment immediately.

• Snake bite ?

Ans. Wash the wound well with water and tie a tight tourniquet i.e. a cloth strip near the wound in such a way that the venom of bite should not reach the vital organs. Victim should be given emotional support and taken to the doctor as early as possible for the anti-venom injection.

• Sunstroke ? 

Ans. Take the patient in a shade or in any cool place. Wipe the body with cold water. Keep the wet cloth on the neck and head. Plenty of water or sherbet should be given to avoid dehydration. If a person feels like vomiting, he/she should be made to lie down on his/ her abdomen with the head turned to one side.

• About the work of a 'Sarpa- Mitra':

Ans. 'Sarpa- mitra' are volunteers who help to save the snakes. If people come across any snake in their vicinity, they usually kill it even before they come to know about its toxicity. Sarpa-mitra go to such places, capture the snakes, rescue, relocate and release them back  into their natural habitats, Sarpa- mitra create awareness about the snakes, try to remove the myths associated with snakes and explain the importance of snakes. During the festivals of Nagpanchami if the snakes are see to be abused. they rescue these snakes too and educate the snake-charmers.

• How is lac obtained from nature ?

Ans. Lac is the secretory material obtained from lac insect. From the body of female lac insect this resinous substance is given out as secretion. When this substance comes in contact with air, it solidifies and forms lac.

• How are pearls obtained ? 

Ans Pearls are formed inside the shells of a bivalve marine animals. If any foreign particle enters the body of this animals, a layer of protective substance called chancre is  deposited around it. This deposition ultimately forms pearl. In the laboratories, artificially a bead is inserted in the body of an animals called pearly oyster. Pearly oyster deposits layers of chancre around this bead. This is how cultured pearly is prepared.

• What should you do to keep your bones strong and healthy ?

Ans. For keeping the bones strong and healthy, we need to take proper diet. The diet should contain vitamin D and minerals like calcium and phosphorus. For obtaining these nutrients, milk, milk products, fruits, green leafy vegetables, eggs and meat should be consumed regularly, Regular exercise, walking, cycling, etc. Will keep the bones strong.

• How many types are there ?

Ans. There are four main types of bones according to their shapes. They are 1) Flat bones 2) Irregular bones 3) Small bones 4) Long bones.

• There is no melanin pigment in our skin.

Ans. If there is no melanin pigment in the skin, our skin will look absolutely white. The harmful ultraviolet rays of the sun will damage our internal organs due to absence of melanin. Melanin gives characteristic hues of color and glow to our body. this will not be seen in the absence of melanin.

• How does sweating help to lower the temperature of the body ?

Ans. The sweat from sweat glands spreads on the surface of the skin. It evaporates due to the heat and at that time, it draws heat from the body. As the evaporation takes place to further, more and more heat is absorbed and then body becomes cooler. Thus sweeting helps to lower the temperature of the body. 

• Which types of motion are seen in birds flying in the sky ?

Ans. The birds flying in the sky show oscillatory motion when they flap their wings. Most of the birds show linear motion. Some like kite display circular motion. Crows are seen moving in random motion.

• Machines are oiled from time to time.

Ans. Machines are used to save our energy and time. The machines working on mechanical forced should work  efficiently. If they are not oiled, the frictional force may be created between the surfaces of this machine, If frictional force is more it will slow down the speed and efficiency of the machine, therefore, machines are oiled from time to time. 

• Which forces are acting upon an airplane taking off into the sky ? 

Ans. When an airplane takes off, it uses mechanical force. The pilot uses muscular force. The weight or gravitational force pulls down the airplane. This opposes the lift created by air flowing over the wing. This is a frictional force. Thrust is generated by the propeller, this is a mechanical force and opposes drag caused by air resistance to the airplane.

• Why should we save energy ?

Ans. Saving energy is the need of the hour. When we produce energy, we need fuel on a very large scale. The fuels are also depleting fast from the earth. By more consumption of energy, lost of carbon dioxide is produced. This leads to global warming and pollution. In order to conserve our environment, we must save energy.

• What is 'green energy'? 

Ans. The energy resources which do not emit smoke and carbon products are called green energy resurgence The energy produced in this way is the green energy.

• What are the non-conventional energy resources ?

Ans. The inexhaustible and continuously available energy resources which were not traditionally used previously re called non-conventional energy resources. e.g. Solar energy, wind energy, tidal energy, hydel power, atomic energy, energy obtained from the oceanic waves.

• Which forms of energy from the sun are used in solar energy devices ?

Ans. In solar cooker, solar heater and solar dryer, the heat energy from the sun is used. While in solar lamps light energy from solar energy is used. In solar cells, solar energy is used to produce electricity.

• Why do you get hungry after physical exercise ?

Ans. Due to exercising, there is movement of muscles and bones. The work done by the body muscles requires energy. This energy is supplied by the heat energy produced by digestion of food. Food is rich in chemical energy. This energy is converted into heat energy in our body. When there is more demand for energy we feel more hungry. Therefore, after exercising we feel hungry.

• Why do we get tired ?

Ans. When due to excessive work, the stored energy in the body becomes low, we get a feeling of tiredness.

• How is energy obtained from cooking gas?

Ans. In the cylinder of cooking gas, the full is in the form of Liquid Petroleum Gas [LPG]. This is propane or butane in its chemical form. This fuel is burnt slowly and it yields heat energy. This heat energy is used for cooking food.

• What is meant by simple machines ? 

Ans. Devices which are used for day-to-day work to perform the work efficiently, in less time and with less effort are called machines. The machines that have only one or two parts and have simple and easy structure are called simple machines.

• Using a machine.

Ans. If machines is used, we can finish the work in less time and with less effort. If machines are not used, we require more time and more effort to complete even the simple tasks.

• How are machines maintained?

Ans. The maintenance of the machines is done in the following way : 1) All the parts of a machine are wiped clean. 2) Oil and other lubricants are applied between the parts that may have friction. This reduces wear and tear of the machines. 3) Machines are not kept covered so that the dust does not settle on them. 4) Metallic parts of the machine are painted externally so that they don't catch rust. 5) Machines are always kept dry.

• How do we come to know that light travels in a straight line?

Ans. The rays of light are seen entering a room through a slit in a door or a small hole in the roof. These rays show dust particles within them. Due to these particles, the path of the light is clearly seen. As the rays move to the ground from the hole in the roof, they are seen to be in a straight line. 

• Due to which property of a surface is image formed ?

Ans. The glossy surface which can reflect light from it can produce the images. When light rays are thrown back from such surface, image is formed.

• When can an object be seen ?

Ans. The light rays from the source of the light, fall on an object. When this light reflects from the surface of the object, it enters our eyes. Therefore we are able to see this object. The luminous objects can be seen as they emit their own light.

• What is a shadow? 

Ans. Shadow is produced by an opaque object. Light does not pass through an opaque object. It does not reach the wall or any other surface on the other side of the object. This part therefore remains dark. This dark area is called the shadow of that object.

• What things are necessary for the formation of a shadow ?

Ans. The following things are necessary for the formation of a shadow. The source of light, an opaque object and a surface on which the shadow falls.

• What are the factors on which the formation of a shadow depend?

Ans. The factors on which the formation of a shadow depend are as follows : 1) source of  light 2) the type of the object 3) the kind of surface 4) the relative distances between the source of light, object and the surface.

Which magnet will you use ?

• Iron is to be separated from trash.  -   Ans. Electromagnet.

• You are lost in a forest.  -                   Ans. Mariner's compass.

• A window shutter opens and shuts continuously in the wind. -

Ans. Permanent magnet.

• The doorbell should ring.   -                Ans. Electromagnet.

• Determine whether a material is magnetic or non-magnetic.

Ans. The material should be taken near to the magnet. If the material sticks to the magnet, the material is magnetic. If it does not stick then it is non- magnetic.

• Explain that magnet has a certain magnetic field.

Ans. Keep a magnet in the center of a paper. Spread iron fillings uniformly on the flat paper. The iron filings will get attracted to the magnet only till a particular region. Beyond this region, the iron filings will not get attracted. The region where iron filings are attracted is the magnetic field, whereas the region from where the iron filing are not attracted, will be the region with no magnetic field. This experiment can give some idea about the extent of magnetic filed of a magnet.

• How is an electromagnet made?

Ans. When an article of iron is wound by a copper wire and the electric current is sent through the wire, the magnetism is produced in this iron article. If the electric current is shut off, the magnetism is lost. This is how temporarily magnetism can be produced by creating electromagnetism.

• From which metals are permanent magnets made ?

Ans. Permanent magnets can be made by a mixture of metals such as iron , aluminum , cobalt and nickel. The material Alnico which is made from aluminum nickel and cobalt is widely used for making permanent magnets.

• What are the practical uses of a magnet ? 

Ans. 1) Pin holder, doorbell, doors of a fridge, car doors, magnets attached to a fridge for decorations are some of the articles in which magnets are used. 2) The crane uses magnets which are very powerful. They are usually electromagnets. 3) The modern medical technique such as MRI (Magnetic Resonance Imaging) also uses magnetism. ATM cards, credit cards and debit cards also have a magnetic strip attached to them. 4) Hard disc of computer, audio and video CD, etc. also use magnetic materials. 

• What is a magnet keeper ?

Ans. The magnet keeper is a bar of soft and pure iron. It is used to protect magnet. This piece is kept in the box in which the magnet is stored. In order to keep the magnetism intact, magnet keeper is used.

• Which celestial bodies form the solar system?

Ans. In the solar system, there is the sun, different planets, their satellites, asteroids. dwarf planets, comets and meteors.

• What is the difference between stars and planets ?

Ans. Stars have light of their own. Therefore, they appear to twinkle. Planets do not have light of their own ; they receive the light from the stars such as sun. Thus their light looks stable. The stars have their own heat and light, planets do not have their own heat and light. Planets move around the stars.

• How many planets are there in our solar system ?

Ans. There are eight planets in our solar system.

1) Mercury 2) Venus 3) Earth 4) Mars 5) Jupiter 6) Saturn 7) Uranus 8) Neptune .

• What is to be found between Mars and Jupiter ?

Ans. Between Mars and Jupiter there is a belt of asteroids.

• Why do we see only one side of the moon ?

Ans. We can see only one side of the moon because the moon rotates about its axis at the same rate that the moon orbits the Earth. The moon is illuminated by the sun and thus we can see only one side of then moon.

• Which planet has a day longer than its year?

Ans. Venus has the longest day of about 243 earth days [i.e. about 5,832 hours] due to its rotations. Whereas it revolves around the sun in approximately 225 earth days.

• Which celestial bodies does a galaxy include ?

Ans. A galaxy includes innumerable stars and their planetary systems. It has many celestial bodies such as clusters of stars, nebulae, clouds of gases, clouds of dust, dead stars, newly born  stars, etc. The Milky Way is our galaxy in which our solar system is included. It has planets, satellites, asteroids, dwarf  planets and meteors.

• What are the types of galaxies ?

Ans. The types of galaxies are according to their shapes. These are spiral, elliptical, barred spiral and irregular.

• Name the different types of stars.

Ans. There is a great variety in stars. Some are very bright, some are faint. There are many colors among the stars. e.g. Blue, white, yellow and reddish. Some stars have varying brightness. Their luminance changes constantly. According to these characters, the stars are of the following subtypes : Sun-like Stars, Red Giants Stars, Super Nova, Binary or Twin Stars and Variable Stars.

• What is a special characteristic of the planet Mars ?

Ans. 1) Mars is the fourth planet in our solar system. 2) It appears reddish as the soil on the Mars contains iron. Hence it is also known as the red planet. 3) The highest and largest mountain in our solar system called Olympus Mons is present on the planet Mars. 4) Mars has two satellites. Its rotation is in about 24 hours and is takes about 1.88 years to revolve around the sun.

• The luminance and the shape of polarity does not remain stable. 

Ans Polaris or pole star is the variable star. Such type of stars constantly contract or expand. When the star expands, it emits less energy. At this time its brightness decreases. On the other hand, When a star contracts, its surface temperature increases and the star emits greater energy and appears brighter. Therefore the luminance and the shape of polar is does not remain stable.

• Jupiter is said to be a stormy planet.

Ans. Jupiter is the largest planet of our solar system. It rotates around itself with a great speed. Huge storms always occur on this planet, therefore Jupiter is said to be a stormy planet.

• Moon is called a satellite.

Ans. Moon is a satellite of the earth. It revolves around the earth. It also undergoes rotations around its own axis. The celestial body  which does not revolve around the sun but revolves around the planet is called satellite. Therefore Moon is called a satellite.

• The comets appear to have a long feathery tail.

Ans. The comets are made up of frozen matter and dust particles. When the comet goes near to the sun, this frozen matter changes into gaseous matter due to the sun's heat. These gases are thrown in the direction away from the sun, as the comet takes the revolution around the sun. Therefore these gases assume a form of long feathery tail.

• In which city is the Taj Mahal located ?

Ans. The Taj Mahal is located in the city of Agra.

• In which continent is the Taj Mahal located ?

Ans. The Taj Mahal is located in the continent of Asia.

• What is a globe ?

Ans. A miniature model of the earth is a globe.

• How much is the angular distance between the Tropic of Cancer and the Tropic of Capricorn ?

Ans. The angular distance between the Tropic of Cancer and the Tropic of Capricorn is 47०. 

• By how many degrees is the earth's axis inclined ?

Ans. The earth's axis is inclined by 23० 30‘.

• What is weather ?

Ans. Short lived atmospheric conditions prevailing at a place and at a given time is weather.

• What is climate ?

Ans. The average weather condition of a place observed over a long period of time is climate of that region.

• What is wind ?

Ans Air moving from high pressure areas towards low pressure areas in a horizontal direction is wind.

• What is called precipitation ? 

Ans. Condensing of vapor in the atmosphere into water droplets or snow particles and their showering on the earth is called precipitation.

• What are the elements of weather ?

Ans. Temperature, air pressure, winds, moisture, precipitation are the elements of weather.

• What are the forms of precipitation ?

Ans. Rainfall, snowfall, hailstorm, etc. are the forms of precipitation.

• Which aspects do get affected by the elements of weather ?

Ans. The aspects like day to day activities and lifestyle. get affected by the elements of weather.

• Why is the climate of Mahabaleshwar cool ?

Ans. As we move upward from sea level, the temperature of air decreases. Mahabaleshwar is located at high altitude (high above the sea level ) in Sahyadri Mountain. Therefore, the climate of Mahabaleshwar is cool.

• Why is the climate near the sea humid?

Ans. 1)Because of the heating of sea water, water vapor gets mixed in the air.2) Air near the sea area having higher temperature holds a greater amount of moisture. Therefore, the climate near the sea is humid. 

• Which device is flat ?

Ans. A map is flat.

• Which device is spherical ?

Ans. A globe is spherical.

• What is the difference between weather and climate ?

Ans.1)Weather is described on the basis of the conditions prevailing at the given time while climate is described on the basis of conditions prevailing over a longer period of time. 2) Weather keeps on changing frequently and we can experience changes in the weather easily. Changes in the climate take place over a longer period. These changes are not perceived so easily.

• What effects do nearness to the sea and height above mean sea level have on the climate ?

Ans. A) The effect of nearness to the sea on the climate : 1) Because of the heating of sea water, water vapor gets mixed in the air. Air near the sea area having higher temperature holds a greater amount of moisture. Therefore, the climate near the sea is humid. 2) In the interior continental regions, the air holds comparatively less amount of moisture. Therefore, the climate in the interior continental region is dry.

B) The effect of height above the mean sea level on the climate : 1) The earth's surface get heat from the sun. As a result, the surface gets heated up. The air near the surface of the earth receives the maximum heat. 2) As we move upward from sea level the temperature of air decreases.

• About air pressure.

Ans. 1) Air has weight. As a result, it creates pressure. It is called air pressure. 2) The lowermost layers of air get subjected to the pressure of the upper layer. Hence the density of the lower layers of air increases. 3) There is greater air pressure near the surface of the earth and it decreases with increasing height. This is vertical air pressure. 4) Temperature zones leads to changes in air pressure. These changes occur in a horizontal manner. This gives rise to winds.

• Why is mineral oil called black gold ? 

Ans. The mineral oil is called black gold because it has blackish color and it is costly.

• At which places is mineral oil mainly found ?

Ans. Mineral oil is mainly found under land surface and also below ocean floor.

• Where is Hight quality coal used on a large scale ?

Ans. High quality coal is used on a large scale in industries and in thermal power stations.

• Which fuels are knows as bio fuels ?

Ans. The fuels originating from the remains of dead plants and animals are known as bio fuels.

• How much is the distance from the earth's surface to its center?

Ans. The distance from the earth's surface to its center is 6373 km.

• By how many degree Celsius does the temperature in the earth's interior increase at a depth of every 32 meters ?

Ans. The temperature in the earth's interior increases by 1▫ C at a depth of every 32 meter.

• How many degree Celsius is the temperature at the center of the earth ?

Ans. The temperature at the center of the earth is around 4000 ▫ c.

• Which energy resource does man use the most ? Why?

Ans. 1) Man uses coal the most. 2) It is because coal is comparatively easily available everywhere in greater quantities.

• Why are energy resources needed ?

Ans. 1) The energy resources are needed to satisfy the needs of man. 2) Energy resources are needed for heating water, for cooking food, for driving vehicles, for running machines, etc.

• Coal.

Ans. Long ago, plant and animals remains got buried due to earth movements. They were then decomposed due to extreme pressure and heat, leaving behind elements, carbon. By this process. coal was formed. Low quality coal is used for cooking. Coke and high-quality coal is used in industries and thermal power stations.

• Mineral oil and natural gas.

Ans. Mineral oil is found under land surface and also below the ocean floor. In most of the mineral oil wells, reserves of natural gas are also found. Mineral oil reserves are limited in nature however it is in greater demand. Therefore its cost is very high. Mineral oil is also called black gold due to its blackish color and high cost. Mineral oil and natural gas are used in thermal power generation.

• Biogas.

Ans. Biogas can be generated from biotic waste materials such as faeces of animals, dead leaves, shells, etc. This energy can be used for domestic needs such as cooking. heating water, lighting lamps, etc. Some farmers have raised biogas plants in their own yards to cater to their domestic needs.

• Atomic energy.

Ans. Splitting of the atoms of minerals like uranium and thorium can be used for power generation. In this process, using very small quantities of minerals, energy can be generated on a very large scale. Only few countries like India, U.S.A., Russia, France and Japan use atomic energy.

• Hydel power.

Ans. Hydel power is the power obtained from the kinetic energy of running water. Hydel power does not cause any degradation of the environment. Also, the water used in generating power can still be used again.

• Wind energy. 

Ans. Nowadays, wind energy is being utilized for power generation. For power generation a wind speed of 40 to 50 kmph is required. Due to this wind speed, the blades of the windmills turn, generating kinetic energy. This kinetic energy is further converted into electricity. This electricity can be used for agriculture, domestic used and industries.

• Solar energy.

Ans. We get light and heat from the sun. India is located in the torrid zone. Therefore, it has a lot of scope for using solar energy. Devices like cookers. lamps. heaters, vehicles etc. can be run on solar power. The generation of solar power depends on the intensity of sunrays and the duration of sunshine.

• Tidal energy. 

Ans. Sea waves and tides are movements of ocean water that go on continuously. A technology has now been developed to generate power with the help of the speed and force of sea waves. The kinetic energy of sea waves and tides is converted into electricity. This energy is pollution-free and everlasting. It can be used on a large scale in a peninsular country like India.

• Geo-thermal energy.

Ans. The temperature in the earth's interior increases by 1~C at a depth of every 32 meters. Man has now developed a process whereby this underground  heat can be utilized to generated power. One such project is located at Manikaran, Himachal Pradesh in India.

• What is 'History' ? 

Ans. History is a coherent account of the significant past events in the progress of human civilization.

• What is meant by peninsula ?

Ans. A region bounded by sea on three sides is called a peninsula.

• Which mountain ranges lie in the north India ?

Ans. Hindukush and Himalayan mountain ranges lie in the north India.

• Where do the rivers Ganga and Brahmaputra meet ?

Ans. The rivers Ganga and Brahmaputra meet in Bangladesh.

• What are the sources of History ?

Ans. All those articles, structures and written records as well as folk tales and folk arts that help us to understand history are called the sources of history.

• The language of vedic literature.

Ans. Sanskrit.

• Meaning of 'vid'.

Ans. To know.

•  What is 'Summary Writing'? 

Ans.  A summary gives the main points of a passage in brief. It does not give details or examples, and is generally written in one paragraph. Sometimes, points may be given for guidance for writing the summary.

     This is called 'Summary Writing'