Green Science 10 Final PDF (2076)

Ways to protect ozone layer Chlorofluorocarbon and oxides of nitrogen are mainly responsible for depleting ozone layer. Thus, the following ways can be taken into practice to protect ozone layer i. Discouraging the use of machines and equipment that use chlorofluorocarbons ii. Encouraging the use of hydroflurocarbon in place of chlorofluorocarbons iii. Reducing the use of chemical fertilizer like nitrogen iv. Using electric vehicles in place of the vehicles operated by diesel and petrol v. Discouraging the burning of plastic materials Industrial gases In the process of industrial production, various poisonous gases, carbon compounds, sulphur dioxide, carbon dioxide, carbon monoxide, nitrous oxide, etc. are also produced. Along with these materials, dust particles, water, Fig. smoke, solid wastes, etc. are also released from industries. These all materials are responsible for polluting atmosphere. Other various 22.6 Smoke released from industries pollutants are produced by the reaction of industrial pollutants. For example, nitric acid is formed from the industrial nitrogen dioxide in the presence of oxygen gas. Similarly, sulphuric acid is formed when sulphur dioxide is mixed with water. Sulphur trioxide is formed when sulphur dioxide reacts with oxygen. On mixing sulphur trioxide with water, sulphuric acid is formed and it reaches the earth with rain water. The falling of various acids like nitric acid, sulphuric acid, etc. on the earth along with rain water is called acid rain. Chemical reactions 4HNO3 (Nitric acid) H2SO3 (Sulphurous acid) 4NO2 + 2H2O + O2 2SO3 (Sulphur trioxide) SO2 + H2O H2SO4 (Sulphuric acid) 2SO2 + O2 SO3 + H2O Effects of industrial gases i. Industrial gases cause dizziness, headache, cough, eye itching, throat problem, chest pain, lungs cancer, etc. ii. Carbon monoxide causes problem in transportation in body tissues. It also causes respiratory diseases like bronchitis, asthma, etc. iii. Air pollution causes obstacle in activities of human muscles. GREEN Science (Geology and Astronomy) Book-10 401

iv. Some industrial gases cause acid rain which is responsible for destruction of metal and calcium carbonate structures. v. The increasing amount of carbon dioxide (CO2) in the atmosphere causes global warming. Key Concepts 1. Climate change is a global problem. Its adverse effects are increasing throughout the world. Climate change affects nature and living beings adversely. 2. The efforts that are paid in Nepal for reduction and adaptation of climate change are called national efforts. 3. The Government of Nepal prepared national adaptation programme in September, 2010. This programme evaluates the climate change and its risks. 4. The efforts paid at international level for adaptation and reduction of climate change are called international efforts. 5. The UN Framework Convention on Climate Change (UNFCCC) is an intergovernmental treaty developed to address the problem of climate change. 6. Agenda 21 is a non-binding voluntarily implemented action plan of the united nations with regard to sustainable development. It is a product of the earth summit (UN Conference on Environment and Development) held in Rio de Janerio, Brazil, in 1992. 7. The international Panel on a Climate Change (IPCC) is a scientific and intergovernmental body. The IPCC developed from an international scientific body, the Adversary Group on Greenhouse set up in 1985 by the International Counsil of Scientific Unions, the United Nations Environment Programme (UNEP) and the World Meterological Organization (WMO) to provide recommendation based on current research. 8. The Kyoto Protocol was historical agreement in which many of the world's industrial nations concluded a verifiable agreement to reduce their emissions of six greenhouse gases in order to prevent global warming. 9. Atmosphere is the thick layer air that surrounds the earth's surface. 10. The uppermost part of troposphere which separates troposphere and stratosphere is called tropopause. 11. Troposphere is also called changeable layer since temperature keeps on changing in this layer on increasing the altitude. 12. Stratosphere consists of ozone layer at its upper surface. Thus, stratosphere is also called ozonosphere. 13. The layer of atmosphere which is situated above stratosphere and below thermosphere is called mesosphere. 14. The temperature of mesophere decreases on increasing the altitude. Mesosphere is the coldest layer of atmosphere. 402 GREEN Science (Geology and Astronomy) Book-10

15. The layer of atmosphere situated above mesosphere and below exosphere is called thermosphere. It extends upto 80km to 720km from the surface of the earth. 16. Ozone layer is present in the stratosphere in the form of the layer of pale-blue gas. It absorbs about 99% harmful solar radiations like UV-rays, X-rays, gamma rays, etc. Ozone layer protects living organisms on the earth from harmful UV-radiations. 17. Ozone layer plays a key role in balancing weather and temperature on the earth. 18. The major chemical responsible for depleting ozone layer is chlorofluorocarbons (CFCS). Besides methyl chloroform, carbontetrachloride and methyl bromide also cause depletion of ozone layer. 19. Ozone layer depletion refers to decreasing the thickness of ozone layer or formation of hole in it. 20. CFCs is a chemical compound which contains carbon, hydrogen, chlorine and flourine. It has not any natural source since it is an industrial chemical. 21. UV-rays cause various diseases like cataract (blindness), skin cancer, breast cancer, sun burn, eye burn, leukaemia, etc. in human beings. Sequential General Exercise 1 1. Choose the best answer from the given alternatives. a. In how many sectors the climate adaptation strategic programme of Nepal has been divided. 3 4 5 6 b. On the basis of which factors the atmosphere is divided into five layers (Troposphere, Stratosphere, Mesosphere, Thermospheres and Exosphere). Density and altitude Density and temperature Density, altitude and temperature Density and humidity c. Which one is called fringe region among the following? Troposphere Mesosphere Exosphere Thermosphere GREEN Science (Geology and Astronomy) Book-10 403

d. Chlrofluorocarbon is mainly responsible for depleting ozone layer. Among the following, which gases cause depletion of ozone layer? Methyl chloroform and oxygen Methyl chloroform and carbon tetrachloride Methyl chloroform and mythyl bromide Methyl chloroform, carbon tetrachloride and methyl bromide e. How is sulphuric acid formed from the industrial sulphur dioxide? By the reaction of sulphur dioxide with oxygen By the reaction of sulphur dioxide with water By the reaction of sulphur dioxide with oxygen and then with oxygen By the reaction of sulphur dioxide with oxygen and water 2. Answer the following questions. a. Make a list of any five national efforts that have been made to reduce the effect of climate change and describe any two briefly. b. Name any five international efforts that are in practice to minimize the adverse impacts of climate change. Explain any two of them briefly. c. Define atmosphere. Name the different layers of atmosphere. d. What is ozone layer? Explain the formation of ozone layer with chemical reactions. e. What does depletion of ozone layer mean? Mention any two causes of depletion of ozone layer. f. Explain any four major adverse impacts of depletion of ozone layer. g. 'Chlrofluorocarbon is mainly responsible for depletion of ozone layer'. Justify this statement. h. Why should we discourage the use of CFC in our daily life? Mention any two reasons. i. The health hazards like skin burn, and skin cancer may be caused due to exposure of our body organs to the sun for a long time. Now, answer the following questions. i. What are the causes of above mentioned health hazards? ii. What can be done to prevent from the above mentioned health hazards? j. What are industrial gases? How do industrial gases pollute atmosphere? Explain briefly. 404 GREEN Science (Geology and Astronomy) Book-10

k. Mention any four adverse impacts of air pollution due to the industrial gases. 3. Differentiate between: i. Trosposphere and stratosphere ii. Stratosphere and mesosphere iii. Troposphere and exosphere 4. Write short notes on: ii. Climate Change Policy, 2067 i. Climate change iv. Layers of atmosphere iii. Kyoto Protocol vi. Ways to protect ozone layer v. Importance of ozone layer vii. Industrial gases Project work 1. What types of activities have been conducted in your locality to minimize the impacts of climate change? Prepare a report on the basis of your research and present it in your classroom. 2. Classify the different layers of atmosphere in a chart paper on the basis of the following data: i. Distance from the surface of the earth ii. Condition of temperature iii. Activities taken place iv. Special features 3. Draw a well labeled diagram to show different layers of atmosphere and explain it briefly. Grid-based Exercise 2 Group ’A’ (Knowledge Type Questions) (1 Mark Each) 1. What is climate change? 2. Write any two national efforts for reduction and adaptation of climate change. 3. When was climate change policy come into practice in Nepal? 4. When did Government of Nepal prepare National adaptation program? 5. When was Kyoto Protocol entered into force? 6. How many layers is the atmosphere divided ? 7. What is tropopause ? What is the average temperature of this layer? Write. 8. In which layer of the atmosphere is the ozone layer found? 9. Write the name of main chemicals that deplete ozone layer. 10. Write any two characteristics of chlorofluorocarbon. GREEN Science (Geology and Astronomy) Book-10 405

11. What is stratopause? What is the average temperature of this layer? 12. Write any two measures to protect ozone layer depletion. 13. What is a greenhouse? Write. 14. Write any two greenhouse gases. 15. What is acid rain ? Group ‘B’ (Understanding Type Questions) (2 Marks Each) 16. Climate change is a global problem, why? 17. Climate change can be reduced in some extent by conserving forests. Justify this statement. 18. Which layer of the atmosphere is responsible for the climate change? Why? 19. Write any two differences between troposphere and exosphere. 20. The temperature of troposphere decreases as the increase in height, why? 21. The use of chlorofluorocarbon in refrigerator is not good, why ? 22. Ozone layer is called a protective layer, why? 23. Write any two differences between stratosphere and thermosphere. 24. The temperature of stratosphere increases as the increase in height, why? 25. The temperature inside an artificial greenhouse is comparatively more than that of outside, why? Group ’D’ (Higher Abilities Type Questions) (4 Marks Each) 26. Describe in brief the climate change, its causes and effects. 27. List the national efforts for reduction and adaptation of climate change and describe any one of them. 28. How is ozone layer depleted? Describe in brief. 29. How does industrial gases increase the temperature on the earth? Describe. 30. Write any four international efforts for reduction and adaptation of climate change and explain one of them. 406 GREEN Science (Geology and Astronomy) Book-10

UNIT The Earth in the 23 Universe Weighting Distribution Theory : 4 Practical: 1 Before You Begin The vast sorrounding space in which all planets, satellites, stars, galaxies, constellations, comets, matter, energy, dust particles, etc. exist is called universe. The solar system exists in the universe. The galaxy in which solar system exists is called milky way galaxy. It is estimated that about 1022 stars are in existence in the universe. Among them, some are super giants, some are giants, some are medium and some are small. The sun is the medium-sized star of the solar system. The earth is one of the planets of the solar system in the universe. In this unit, the brief description of the structure of the solar system, comets, meteors, constellations, galaxies and artificial satellites is presented. Learning Objectives Syllabus After completing the study of this unit, students will be able to: • Solar system • Planets i. explain the shape and structure of solar system with labelled • Comets figure. • Meteors • Constellations ii. explain comets and meteors that exist in solar system. • Galaxy iii. describe galaxies with figures. • Zodiacs iv. describe zodiacs with figure. • Satellites v. evaluate scientific facts regarding to zodiacs. • - Natural satellites vi. explain natural and artificial satellite. • - Artificial satellites Glossary: A dictionary of scientific/technical terms universe : the vast surrounding space that contains everything like galaxy, constellations, solar system, etc. planets satellites : the heavenly bodies that revolve around the sun galaxy : the heavenly bodies that revolve around the planets omen : the system of stars, dust, particles, etc. : something that is believed to be a sign or warning of something that will happen in future GREEN Science (Geology and Astronomy) Book-10 407

Solar System The family of the sun that consists of all planets and their satellites, comets, meteors, asteroids, etc. is called solar system. Solar system includes the sun, eight planets, their satellites, celestial bodies like comets, meteors, asteroids, electrically charged atoms, Fig. Fig. (plasma), dust particles, etc. The sun is the central member 23.1 of the solar system. All the Solar system members of the solar system revolve around the sun in elliptical orbits in the same direction due to the gravitational force of the sun. The Sun The sun is a medium sized star that is situated in the center of solar system. The sun has the greatest mass in the solar system. The approximate mass of the sun is 1.99 × 1030kg with average diameter 1.3924 × 106 km. The sun is 2.5 × 104 light year far from the center of milky way galaxy. The distance between the sun and the earth is 1.5 × 108km. It is estimated that the surface temperature of the sun is about 5700°C and its core 23.2 The Sun temperature is 1.5 × 107°C. The sun is the major source of all the energy of the solar system. The sun emits energy in the form of heat and light continously by the thermonuclear fusion reaction. The sun emits visible waves, infrared, ultraviolet rays, x-rays, radio wave and other radiations. The charged particals called plasma are produced from the sun in the form of solar wind. The speed of solar wind is about 500km/s. The amount of hydrogen in the sun is about 70 percent. The age of the sun depends upon the amount of hydrogen in it. In the center of the sun, hydrogen atoms are continuously combining to form helium atoms. Planets Do You Know Planets are the members of the solar The word planet has been taken from the system. The heavenly bodies which Greek word \"Wanderer\" because they revolve around the sun in elliptical orbits revolve around the sun. are called planets. Examples, the earth, 408 GREEN Science (Geology and Astronomy) Book-10

jupiter, saturn, mars, neptune, etc. All planets revolve around the sun in elliptical orbits. They do not have their own source of light, but they shine by reflecting the light received from the sun. The eight planets of the solar system are mercury, venus, earth, mars, jupiter, saturn, uranus and neptune. Among these eight planets, mercury, venus, earth and mars are inner planets and jupiter, saturn, uranus and neptune are outer planets. Except mercury and venus, all six planets have their natural satellites. Since all planets revolve around the sun in their elliptical orbit, their positions among stars keep on changing. The name for these bodies is given planet since they are in continuous movement. In Greek 'planet' means 'wanderer'. The planets have their own velocity, temperature, atmosphere and satellites. The brief description of eight planets of the solar system is presented below. Mercury In solar system, mercury is the smallest planet. This planet is closest to the sun. Thus, it is difficult to observe it without the telescope. It has no atmosphere and satellite. Mercury is closest to the sun. So it is very hot during the day. It revolves around the sun faster than other planets due to its less distance from the Sun. Fig. Fig. It completes one rotation in its axis in 59 days in its orbit. One region of this planet always faces towards the sun. The 23.3 diameter of this planet is 4851km and Mercury its temperature varies between 427°C and 170°C. There are many craters on the surface of Mercury that are formed due to meteor shower. Mercury is located about 5.8 × 107 km far from the sun. It completes one revolution around the sun in 88 days. Mercury can be seen in the western sky before sunrise and after sunset for a short time. Venus 23.4 Venus is the nearest planet to the earth. Venus It is called twin planet of the earth since it has equal mass and shape to the earth. It is the brightest planet in the solar system. It is visible in the eastern sky in the early morning and in the western sky in the evening. Thus, venus is called morning and evening star. Its diameter is 12035 km and its temperature is 480°C. It has no satellites. The atmosphere of venus contains large amount of CO2 and clouds of H2SO4. Thus, it absorbs solar radiations. Venus has black spots in its GREEN Science (Geology and Astronomy) Book-10 409

surface which can be seen from the earth. Do You Know It is 10.7×107km far from the sun. It takes around 225 days to complete one revolution Mercury is the smallest planet of the around the sun and it makes one complete solar system. rotation in its own axis in about 243 days. Venus is the closest planet to the earth. Venus is also called morning star and evening star. Earth The earth is our home planet. It is the fifth biggest planet in the solar system. It is the third planet in terms of its distance from the sun. Among all planets, the earth is the most suitable for the existence of living beings. The average temperature of the earth's surface is about 15°C. The earth contains 71% water, and 21% oxygen. Thus, the Fig. Fig. earth is the only planet which supports survival and existence of life on it. The 23.5 natural satellite of the earth is moon. The Earth diameter of the earth is about 12,672km. It is 14.88×107km far from the sun. It takes around 365 days to make a complete revolution around the sun and about 24 hours to rotate in its own axis. The earth contains the gases like oxygen, carbon dioxide and nitrogen in its atmosphere. It has protective layer of ozone gas which prevents living organisms on the earth from the ultraviolet radiations emitting from the sun. The earth appears blue when viewed from the outer space due to the reflection of light from the water body from the earth. The earth is called a green planet due to the presence of green plants in it. Mars Mars is the fourth planet in terms of its distance from the sun. Its diameter is half of that of the earth. It has two natural satellites deimos and phobos. The surface of mars can be observed in detail from the earth with the help of telescope. The diameter of mars is about 6,742km. It is about 22.56 × 107km far from the sun. Mars takes 687 days to make one complete revolution around the sun. It takes around 24 hours 37 23.6 minutes to complete one rotation in its Mars axis. Mars has more amount of carbon dioxide and less amount of oxygen. The temperature of this planet is similar to that of the earth during day. But its temperature falls below –38°C during the night. Mars is also 410 GREEN Science (Geology and Astronomy) Book-10

called red planet due to the presence of light red coloured mineral rock called limonite in it. It can be easily identified in the sky due to its red colour. The mars has big craters and volcanoes. There are black spots in the one-third part of the mars. These black spots are named as oceans of the mars, however, it has no water at all. In two sides of this planet, there are two white polar caps made of ice of gases. The atmosphere of the mars contains traces of carbon dioxide, hydrogen, oxygen and nitrogen. The survival of living beings is not possible on the mars since its atmosphere has too little oxygen. Jupiter Jupiter is the biggest planet of the solar system. In terms of distance from the sun, it is the fifth planet. Jupiter is about 319 times greater than the earth. The major gases found in the atmosphere of the jupiter are hydrogen and helium. The surface of the jupiter is not visible from the outside since it is covered with Fig. Fig. thick clouds of methane and ammonia. The diameter of the jupiter is about 1.13904×106km and it is 76.8×107km 23.7 far from the earth. Jupiter takes about Jupiter 12 years to make one complete revolution around the sun. It takes 9 hours 55 minutes to make one complete rotation in its axis. Among all planets, the jupiter has the largest number of satellites. The jupiter has 63 known satellites. Among them Ganymede is the largest. The average temperature of this planet is –143°C. Jupiter has a great red spot in its cloud. Astronomers have estimated that this red spot have been created due to the atmospheric hurricane. Saturn Saturn is the second largest planet after jupiter in the solar system. It is the sixth planet in terms of its distance from the sun. Saturn is surrounded by three elliptical rings with small divisions in each ring. The elliptical rings are made of fragments of ice moving around the planet. Saturn takes 10 hour 30 minutes to rotate in its axis. Saturn has made the angle of 270° with the surface of the axis. Thus, days and nights are not equal 23.8 in all places. The staurn has 62 known Saturn satellites. Titan is the largest satellite among the known satellites of the saturn. The diameter of titan is 5,140km. The saturn has its own atmosphere which contains hydrogen, helium and nitrogen gases. GREEN Science (Geology and Astronomy) Book-10 411

Uranus Uranus is the third largest planet of the solar system. It is the seventh planet in terms of its distance from the sun. It is the first planet discovered with the help of telescope. The diameter of the uranus is about 50442km and it is about 288×107km far from the sun. The atmosphere of uranus contains the gases like hydrogen, helium and methane. The Fig. Fig. Fig. surface temperature of uranus is –216°C. Uranus is made up of liquid and gases. 23.9 It is made up of cloud of minute crystals Uranus of methane, hydrogen and helium gas. It is believed that a rocky core is present in the center of uranus and water lies beneath the level of ammonia. Uranus has 27 known satellites. It rotates from the east to the west in its axis. Neptune 23.10 Neptune is the eighth planet in terms of Neptune its distance from the sun. It is the farthest planet from the sun in the solar system. The surface of the neptune contains hydrogen, helium, neon, silicate and water. The surface of the neptune is not solid and hard like that of the earth. This planet is made up of large amount of liquid and gases. Neptune has a rocky core. A black spot in the size of the earth can be seen in neptune. Neptune has 14 known satellites among which triton is the biggest one with diameter 2705km. Comets The broom shaped shining objects with 23.11 bright head that revolve around the sun are called comets. We can observe comets Comets in sky at night. Comets are members of solar system. They are made up of gases, dust and ice. The head of a comet is made up of ice. Comets do not have their own source of light. They reflect light from the sun. They revolve around the sun in their fixed orbit. A comet has mainly three parts, viz. nucleus, coma and tail. 412 GREEN Science (Geology and Astronomy) Book-10

The central part, i.e. nucleus is made by freezing gas, ice and dust particles, coma is made up of gas and dust particles around the nucleus. The coma is covered with the cloud of hydrogen gas. A comet develops a long glowing tail and becomes visible to us when it approaches the sun. The ice remaining outer part of a comet gets melted and changes into vapour due to solar radiations. The solid materials emit out of the comet in the form of dust particles. The gases and ice particles are blown in the opposite direction of the sun due to solar wind and seen in the form of tail due to the solar radiations. Most of the comets can be seen with the help of Do You Know telescope. The comets can be seen with naked eyes in the form of tails when they approach near the The charged atomic particles that sun. After the interval of few years, comets can be emits from the sun with a high seen in the eastern sky before rising the sun and in speed is called solar wind. the western sky after sun set. But, after few days the comets slowly get lost when they become far from the sun. Some information related to comets is presented in the following table. S.N. Name of comets First observed year Time taken to revolve the sun (years) 1. Halley's comet 240 BC 76 years 2. Temple-tutle 1366 AD 33 years 3. Enke 1786 AD 3.3 years 4. Schwasman-washman 1927 AD 15 years 5. Bennet 1969 AD - 6. Shoemaker levy 1993 AD Destructed in 1994 AD by colliding with the jupiter Meteors Meteors are the pieces of stone or metal Fig. that enter the earth's atmosphere in the form of streaks of light and disappear 23.12 within a few seconds. Meteors are called shooting stars or falling stars since Meteor meteors are seen as fast falling stars from one direction to another in the sky. The big and bright falling of meteor is also called fire ball. Either the meteors have been originated with the origination of the solar system or they are left behind by the comets. When the heavenly body enters the gravitational region of the earth, with high speed, heat is produced on them due to the friction between the body and air in the atmosphere. As a result, burning object is seen in the form of streak of light in the atmosphere. The GREEN Science (Geology and Astronomy) Book-10 413

materials of the body are converted into gas or vapour and gets lost within a short time. This process is called falling of meteors. Sometimes, big meteors do not burn completely and may reach the surface of the earth. Such bodies that reach the earth's surface are called meteorites. Meteorites can be classified into three groups depending upon the composition of material. They are stony meteorites, iron meteorites and stony iron meteorites. The meteorites having more amount of silicon than iron and Fig. Fig. Fig. magnesium are called stony meteorites. Similarly, iron meteorites contain more amount of iron and negligible amount of 23.13 silicon. Likewise, the meteorites having Crater in Arizona, USA almost equal amount of iron and silicon are called stony iron meteorites. The meteorites which are found on the earth are iron meteorites. Big meteorites create craters on the surface of the earth. The meteorites of the mass 100gm to 20,000kg are found on the earth so far. The study of the meteorites helps come to the conclusion of the structure of the planets in Astrology and Astronomy. A big meteorite was fallen in Arizona of the USA before fifty thousand years. The diameter of this meteorite was about 1265m with thickness 174m. It created a deep crater which can be seen even today also. The big meteorite which was fallen in Namibia has the weight of 60 metricton. It is called hoba. It is estimated that about 25 crore meteors enter the atmosphere. The 23.14 speed of meteors is 35km/s to 95km/s. Meteor shower in polar region It is also estimated that about 500 meteorites fall on the surface of the earth in the period of one year. Large number of meteors fall near the north pole and south pole of the earth. Thus meteor shower can be seen in the polar regions of the earth. Constellations Constellations The groups of stars which form a fixed pattern are called constellations. They are found in different shapes and patterns. Astronomers has named 88 constellations so far. They have fixed patterns throughout the year. So, they are easily recognizable in the sky. Some constellations can be seen in particular 23.15 season since the earth revolves around 414 GREEN Science (Geology and Astronomy) Book-10

the sun. Different constellations can be seen from north and south hemisphere of the earth at the same time. In ancient time, the constellations were named after gods, heroes, animals, etc to which their patters resemble. For example, Ursa major, ursa minor, orion, leo, libra, pisces, scorpio, cassiopeia, etc. These names were given by the people of ancient Greece, Rome, etc. Similarly, during the period of 1400 to 1700 AD, the sailors named the constellations seen on their ways to southern hemisphere after the names of scientific materials, animals, etc. For example, Tucana, Telescopian, Musca, etc. The astronauts have classified the sky into different constellations and named 88 constellations. For example, ursa major, leon, orion, etc. Ursa Major Ursa major is called great bear since its pattern Fig. Fig. Fig.23.16 is estimated to be resembled bear. In Latin, the meaning of 'ursa' is 'woman'. Ursa major is also called Ursa Major 'saptarishi' since it has seven stars. Ursa major can be seen in the northern sky in the months of Baishakh and Jestha at night. Ursa Minor Ursa minor resembles that of ursa major and is 23.17 called the pattern of little bear. It is also called laghu spatarishi since it has seven bright stars. In ursa minor, the stars are closer to each other. The pattern of ursa minor is similar to little bear. Ursa Minor Orion The pattern of orion resembles a hunter. It has also seven stars. Orion can be seen in the sky in the month of Poush/Magh in winter season. 23.18 Zodiacs Orion Among 88 constellations, 12 constellations that can be seen in the path of the sun are named as zodiacs. They are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricorn, Aquarius and Pisces. GREEN Science (Geology and Astronomy) Book-10 415

Fig. 23.19 12 Zodiac signs Some superstitions related to zodiacs are given below: 1. There are only 12 zodiacs, but the number of people is billions. Thus, there is not any scientific reason to forecast the future of the people by studying the zodiac on the basis of the name of the people. 2. There is no any scientific reason to say that the attitude of the people resembles their zodiacs. But, astrologers interpret people's attitude according to their horoscope. 3. There is no any scientific reason to see the good omen of the people or work according to the zodiac. But seeing good omen according to the zodiac is the practice in our society. 4. There are many examples of unsuccessful conjugal lives of the people that have been matched according to their zodiac signs. But it is still in practice in our society. 5. In our society, it is the customary of wearing rings according to zodiac signs. There is no any scientific reason to prove that these rings bring fortune to the people who wear them on the basis of their zodiac. Thus, it is necessary to go for the scientific reason behind everything rather than believing blindly in the superstitions prevalent in our society. Galaxy The billions of stars in the space have different clusters or groups. A vast cluster of billions of stars in the universe is called a galaxy. In other words, a galaxy is a vast system of stars that contains dust particles and gases isolated from the similar system in the space. A large number of galaxies are extended in the universe. The diameter of such galaxies ranges from 100 light year to 10 thousand light year. The stars in the galaxy revolve round a common centre called galactic centre. The solar system is situated in the milky way galaxy. We can see masses of gases in the form of collection of a large number of stars in 416 GREEN Science (Geology and Astronomy) Book-10

centre of milky way from the earth. This is called milky way galaxy. It is known that there are about 1011 galaxies in the universe. 23.20 Fig. Fig. Galaxy Fig. On the basis of shape, galaxies of the universe are classified into spiral galaxies, elliptical galaxies and irregular galaxies. Spiral galaxy The galaxy having spiral shape is called spiral galaxy. There are spiral arms around the central part of spiral galaxy. Spiral galaxies contain a large amount of gases and dust particles. These galaxies are brighter than other galaxies. The examples of spiral galaxies are milky way galaxy, andromeda galaxy, etc. Milky way galaxy is a spiral galaxy that 23.21 Spiral galaxy contains about 1011 stars. It has a disc in its middle part which is thinner at the edges. The cloud of dust is found in this galaxy. The mass of milky way galaxy is about 1.33×1011 times greater than that of mass of the sun. Elliptical galaxy The round and oval shaped galaxies are 23.22 called elliptical galaxies. They contain less amount of interstellar matter. A bright light is produced in the middle of these galaxies and the light becomes dim at the edges. The stars of elliptical galaxies are very old. Ellptical galaxy GREEN Science (Geology and Astronomy) Book-10 417

Irregular galaxy The galaxies having irregular shape are called irregular galaxies. They have neither elliptical nor spiral shapes. Irregular galaxies are less brighter than the spiral galaxies. Satellite Fig. Fig.23.23 Irregular galaxy The heavenly body which revolves around the planet in its own orbit is called a satellite. Satellites have not their own light. They shine by reflecting the light received from the sun. Satellites are divided into two categories: Natural satellites and Artificial satellites. Natural satellites The satellites that created in nature themselves are called natural satellites. They revolve around the planets continuously. The moon is only the natural satellite of the earth. Mercury and venus have no satellites. The total number of satellites of the planets is 173. Moon Moon is the natural satellite of the earth. The distance between the earth and the moon is about 384,400km. The diameter of the moon is 3456km and the surface area of the moon is 3.7940000×107km2. The moon takes 27 days 7 hours 43 minutes and 11.5 seconds to complete one round around the earth. This period is called sidereal month. Similarly, the 23.24 period of 29 days 12 hours 44 minutes and Moon 2.8 seconds from one full moon to the next full moon is called synodic month. The moon has no atmosphere and the gravity of the moon is 1/6 times less than that of the earth. Planets of solar system and their satellites Name of the planet Number of satellites 0 Mercury 0 Venus 1 (Moon) Earth 2 (Phobos and Deimos) Mars 67 (Europa, IO, Callisto, etc.) Jupiter 62 (Titan) Saturn 27 (Miranda, Ariel, etc.) Uranus 14 (Triton, Nereid, etc.) Neptune 418 GREEN Science (Geology and Astronomy) Book-10

Artificial Satellites The satellites made by humans that revolve around the earth are called artificial satellites. These satellites are launched to the space by human beings. Some examples of artificial satellites are sputnik, INSAT, METSAT, etc. Artificial satellites are launched in a Fig. fixed distance from the earth's surface in space with the help of rocket. The energy 23.25 in the artificial satellites is provided by the solar battery. The artificial satellites Artificial satellites are launched in geostationary orbit which is 36,900km far from the surface of the earth. The purposes of launching artificial satellites in space are given below: i. To find out more facts about solar system, stars, etc. ii. To get radio, TV, telephone signals across the world for communication iii. To forecast weather iv. To conduct experiments that are not possible on the earth v. To find other organisms in outer space vi. To spy for military purposes vii. To survey natural resources viii. To establish research laboratory on the moon and the create artificial spaceship in the future ix. To study the space and different regions of the earth Key Concepts 1. The vast surrounding space in which all planets, satellites, stars, galaxies, constellations, comets, matter, energy, dust particles, etc. exist is called universe. 2. The sun is the medium star of the solar system. The earth is one of the planets of the solar system in the universe. 3. The family of the sun that consists of all planets and their satellites, comets, meteors, asteroids, etc. is called solar system. 4. The heavenly bodies which revolve around the sun in elliptical orbits are called planets. 5. Among eight planets, Mercury, Venus, Earth and Mars are inner planets and Jupiter, Saturn, Uranus and Neptune are outer planets. 6. Among all planets, the earth is the most suitable for the existence of living beings. 7. The broom shaped shining objects with bright head that revolve around the sun are called comets. GREEN Science (Geology and Astronomy) Book-10 419

8. Meteors are the pieces of stone or metal that enter the earth's atmosphere in the form of streaks of light and disappear within a few seconds. 9. Sometimes, big meteors do not burn completely and may reach the surface of the earth. Such bodies that reach the earth's surface are called meteorites. 10. The groups of stars which form a fixed pattern are called constellations. 11. In ancient time, the constellations were named after gods, heroes, animals, etc to which their patters resemble. 12. Among 88 constellations, 12 constellations that can be seen in the path of the sun are named as zodiacs. They are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricorn, Aquarius and Pisces. 13. A vast cluster of billions of stars in the universe is called a galaxy. In other words, a galaxy is a vast system of stars that also contains dust particles and gases isolated from the similar system in the space. 14. The galaxy having spiral shape is called spiral galaxy. There are spiral arms around the central part of spiral galaxy. 15. Milky way galaxy is a spiral galaxy that contains about 1011 stars. It has a disc in its middle part which is thinner at the edges. 16. The round and oval shaped galaxies are called elliptical galaxies. 17. The galaxies having irregular shape are called irregular galaxies. 18. The heavenly body which revolves around the planet in its own orbit is called a satellite. 19. The satellites that created in nature themselves are called natural satellites. They revolve around the planets continuously. 20. The moon takes 27 days 7 hours 43 minutes and 11.5 seconds to complete one round around the earth. This period is called sidereal month. Similarly, the period of 29 days 12 hours 44 minutes and 2.8 seconds from one full moon to the next full moon is called synodic month. 21. The satellites made by humans that revolve around the earth are called artificial satellites. Sequential General Exercise 1 1. Choose the best answer among the given alternatives. a. Which has the greatest mass in the solar system? Earth Sun Jupiter Venus 420 GREEN Science (Geology and Astronomy) Book-10

b. Which one is the diameter of the earth? about 12,672km about 13,672km about 14,672 km about 15,672 c. What is the total number of constellations known so far. 89 88 86 85 d. How many satellites the jupiter has? 67 66 68 69 e. Which one of the following is the artificial satellite? Europa Sputnik Aerial Deimos f. How many stars does the milky way galaxy contain? about 109 stars about 1010 stars about 1011 stars about 1012 stars 2. Answer the following questions. a. What is the universe? What does it consist of? b. Define solar system. What are its members? c. What are planets? Name eight planets of the solar system. d. The earth is called green planet and the mars is called red planet, why? e. The outer surface of the Jupiter is not visible, why? f. What are comets? How are they visible to us? Explain. g. 'Meteors are called falling stars or shooting stars'. Justify this statement. h. What are constellations? Differentiate between ursa major and ursa minor. i. What does galaxy mean? Name three types of galaxies and explain any one of them. j. Mention any five purposes of launching artificial satellites to the space. 3. Write short notes on: b. Moon a. Venus GREEN Science (Geology and Astronomy) Book-10 421

c. Satellite d. Orion e. Milky Way Galaxy f. Meteorites 4. Differentiate between: a. Comets and meteors b. Inner planets and outer planets c. Sidereal month and synodic month d. Galaxy and constellation e. Natural satellite and artificial satellite Project work Prepare a model structure of solar system and present at in your classroom for the discussion on it in detail. Grid-based Exercise 2 Group ’A’ (Knowledge Type Questions) (1 Mark Each) 1. What is solar system? 2. What is Astronomical Unit? 3. Name any one natural satellite of the given planets. i. Saturn ii. Jupiter [Ans: (i) Titan (ii) Callisto] 4. Define satellite. 5. Write any two features of the moon. 6. Name the following celestial bodies: i. Planet having polar caps [Ans: Mars] ii. Planet having big black spot [Ans: Neptune] 7. Name any one natural satellite of the given planets. i. Mars ii. Uranus [Ans: (i) Phobos (ii) Ariel] 8. What is galaxy? 9. What is a constellation? 10. What are zodiacs ? 11. What is synodic month? 12. How many kilometers are there in 1 AU ? (Ans: 15 crore kilometers) 13. Write the name of largest satellite of Saturn and name the gas abundantly found in its atmosphere. (Ans: Titan, Nitrogen) 14. What is fire ball ? 15. What is meteor shower? 422 GREEN Science (Geology and Astronomy) Book-10

Group ‘B’ (Understanding Type Questions) (2 Marks Each) 16. Write any two differences between outer planets and inner planets. 17. A comet is not actually a star, why? 18. Write any two differences between galaxy and constellation. 19. Write any two differences between meteor and meteorite. 20. Mars is called a planet and sun is called a star, why ? 21. Give reason: i. The surface temperature of the Mercury reaches very high (about 420°C). ii. It takes about 248 years for the pluto to revolve round the sun. 22. A meteor disappears before reaching the earth’s surface, why? 23. The tail of comet is increased as it approaches near the sun, why ? 24. Differentiate between constellation and zodiac. 25. A meteor is finished before reaching the earth’s surface, why? Group ‘D’ (Higher Abilities Type Questions) (4 Marks Each) 26. Write a short note on Milky way galaxy. 27. What do you know about big-bang theory? Describe in brief. 28. Introduce zodiacs and explain any two zodiacs with figure. 29. Study the table given below and identify A, B and C. A This planet is red in colour and has two white polar caps. B Although it does not have light of its own, it is the brightest object in the sky. C This is an ice ball that orbits the sun and looks like a broom when it approaches the sun. 30. What is a comet? How is its tail formed? Describe in brief. What is a meteor? Why does a meteor last for a very short time in space? GREEN Science (Geology and Astronomy) Book-10 423

Specification Grid Subject: Compulsory Science Full Marks: 75 Time: 2:15 hrs. S.N. Area Topics K U A HA Total Remarks Marks 1. Physics 1. Force 2. Pressure 3. Energy 5×1 4×2 2×3 1×4 23 4. Heat 22 5. Light 6. Current Electricity and Magnetism 2. Chemistry 7. Classification of Elements 4×1 4×2 2×3 1×4 8. Chemical Reaction 9. Acid, Base and Salt 10. Some Gases 11. Metals 12. Hydrocarbon and Its Compounds 13. Materials Used in Daily Life 3. Biology 14. Invertebrates 15. Human Nervous and Glandular System 16. Blood Circulatory System in Human Body 17. Chromosomes and Sex 5×1 4×2 2×3 1×4 23 1×4 Determination 7 38 18. Asexual and Sexual 75 Reproduction 19. Heredity 20. Environmental Pollution and Management 4. Geology 21. History of The Earth and 22. Climate Change And 1×1 1×2 – Astronomy Atmosphere 23. The Earth in the Universe Total Question's Number 15 13 6 4 Total Marks 15 26 18 16 424 GREEN Science (Geology and Astronomy) Book-10

Secondary Education Examination (SEE) New Model Questions (Issued by CDC) Subject: Compulsory Science Time: 2:15 hrs. Full Marks:75 Note: Attempt all the questions. Group A 1. Write short answer to the following questions. 15×1=15 a. Define Universal Gravitational Constant ‘G’. b. State Pascal’s law. c. What are the types energy sources based on time of replacement? Write their names. d. What is shortsightedness? e. Define 1 unit of electricity. f. State the Modern Periodic Law. g. What is meant by combination reaction? h. Name any one base with its molecular formula. i. Write two ores of aluminium metal. j. Name two types of silkworms cultivated in Nepal. k. What is hormone? l. What is chromosomal disorder? m. Name any two organisms which are reproduced by multiple fission. n. What is mutation? o. Define ozone layer. Group B 13×2=26 2. Study the given diagram and answer the following questions. 12 N 0.5+0.5+1 a. What is the weight of weighted object in air? (Ans: 14 N) b. How much upthrust is exerted by the liquid on that object? c. Calculate the mass of the object. (Ans: 1.4 kg) 2N 3. Write any two points to justify that the urbanization brings energy crisis. 4. Deserts are very hot during the day and very cold during the night. Give reason. 5. Which type of transformer is given in the figure? Which Secondary substance is used to laminate its core? The number of turns Primary winding of primary coil and the number of turns of secondary coil in winding a transformer are never made equal, why? 0.5+0.5+1 6. What is the cause for placing Calcium in IIA group of the modern periodic table? 7. How does heat enhance the rate of chemical reaction? Explain in short. 8. How is saturated hydrocarbon differed from unsaturated hydrocarbon? Write any two differences. 9. Excessive use of chemical fertilizers causes chemical pollution. How? 10. Honey bee is very important insect for human beings and plants. Write any two reasons. 11. Write any two differences between cerebrum and cerebellum. 12. What preventive measures should be adopted for the disease diabetes? GREEN Science (Geology and Astronomy) Book-10 425

13. Why vegetative propagation is beneficial to the farmers? Justify it with two reasons. 14. Why does the tail of a comet visible when it approaches near the sun? Explain in short. Group C 6×3=18 15. If the mass of the moon is 7.2×10²² kg and radius is 1.7×106m, what will be the acceleration due to gravity of the moon? What will be the weight on the moon of a person having 60kg mass? 16. Study the given table of specific heat capacities of the three different substances and answer the following questions. substance Specific heat capacity A 910 J/kg°C B 380 J/kgC C 470 J/kgC a. What is meant by specific heat capacity of the substance A is 910 J/kg°C? 1 b. Which one of the given substances will gain more temperature while heating equal mass of all the three substances with equal amount of heat? 1 c. Which will go down more in depth while keeping equal mass at the three substances heated for the same temperature of 100°C and kept on a wax slab, why? 1 17. In what way we use the neutralization reaction in our daily life? Write any three examples. 18. Write any three applications of ceramics. 19. How does artificial reproduction help in the excess production of fruits? 20. How would you conserve and manage the sources of water? Group D 4×4=16 21. Complete the ray diagram given alongside. Also mention the O F 2F any two natures of the image thus formed. If the power of a 2F F hand lens is +5D, what should be the distance between hand lens and the book to read it properly? 22. The given figure shows the laboratory preparation of ammonia gas. Answer the following questions after observing the given figure. a. Write the balanced chemical reaction of laboratory preparation of ammonia gas by this method. b. Why the mouth of hard glass test tube is inclined downward? c. Ammonia gas cannot be collected over water. Why? d. Which colour of litmus paper can help to confirm that the gas jar is filled with ammonia gas? 23. Draw a chart to show both phenotype and genotype of the result obtained in the first and second filial generation of offspring of mouse, having black colour and white colour according to Mendel’s experimental result. With the help of the same chart. Write the ratio of phenotype and genotype of second generation. 24. Explain the evolution process occurred on the Mesozoic and Cenozoic era. Also mention their differences. *** 426 GREEN Science (Geology and Astronomy) Book-10

MODEL QUESTION SET 1 All the questions are compulsory. Group ‘A’ 15x1=15 1. Write short answers to the following questions: 1 1 a. State Newton’s universal law of gravitation. 1 1 b. State Archimedes’ principle. 1 1 c. What is nuclear fission reaction? 1 1 d. What is the focal length of a lens ? 1 1 e. What type of transformer is called step-down transformer ? 1 1 f. Mention the position of hydrogen in the Modern periodic table. 1 1 g. Give one example of displacement reaction. 1 13x2=26 h. What type of salt is called hydrated salt ? Give one example. 5N i. Write the name of metals obtained from haematite and chalcopyrite. 2 j. Write any two characteristics of eggs of silkworm. k. Write any two hormones secreted by thyroid gland. l. Write any two symptoms of Down’s syndrome. m. What is tongue grafting ? n. Write down Mendel’s law of purity of gametes. o. Write any two ways of identification of fossils. Group ‘B’ 2. Study the given figure and answer the following questions: i. What is the upthrust acting on the stone immersed in water? (Ans: 25 N) 20 N ii. On which principle is the given experiment Water based? Stone iii. What is the weight of the stone. 3. The use of hydroelectricity should be increased rather than that of mineral oil. Justify this statement. GREEN Science (Geology and Astronomy) Book-10 427

4. Wind blows towards land from the sea during day time and towards sea from land at night, why? 2 5. Which type of voltage is converted by the 1000 turns transformer? Name the type of the transformer 2 220 V shown in the given diagram. 320 V 6. Write any two differences between p-block and d-block elements. 7. The rate of a chemical reaction increases on increasing the concentration of reactants, why? 8. Propane is called a saturated hydrocarbon but propene is called unsaturated hydrocarbon, why? 9. The organic fertilizer is better than chemical fertilizer, clarify with two reasons. 10. Why are eggs of silkmoth stored below 18°C in winter season? 11. Write any two differences between exorine gland and endocrine gland. 12. The wall of artery is thicker than vein, why ? 13. Write any two reasons that, why Mendel selected pea plants for his experiment? 14. Mention any two methods of identification of fossils. Group ‘C’ 6x3=18 15. The mass and radius of Jupiter is 1.9 x 1027 kg and 71 x 106 m respectively, find the acceleration due to gravity of it. What will be the weight of an object having mass 75 kg on that planet ? (Ans: 25.13 m/s²) 16. Study the given table and answer the following questions. 1+1+1 i. The specific heat capacity of metal ‘C’ is 380 J/ Metal Specific heat capacity kg°C. What does it mean? A 140J/kg°C B 460J/kg°C ii. If the same amount of heat energy is given to C 380J/kg°C the same mass of all three metals at the same temperature, which one will gain the lowest temperature? Why? iii. Which metal will penetrate into the greatest depth if each with equal mass is put on a wax slab after heating to 75°C each? Why? 17. Name any three acids which are used in our daily life. Also, write an application of each. 428 GREEN Science (Geology and Astronomy) Book-10

18. Write any three ways to get rid of chemical pollution. 19. ‘Vegetative propagation is more beneficial for the farmers.’ Write any three reasons. 20. Mention any three effects of water pollution. Group ‘D’ 4x4=16 21. Redraw the given diagram and complete the ray A diagram. Also, write four nature of the image thus B OF 2F 2F formed. The focal length of a convex lens is 60 cm. F Calculate the power of the lens. (Ans:1.66D) 22. Study the given figure and answer the following questions. i. Name the gas which is Dil. hydrochloric acid Delivery tube being produced in the Thistle funnel diagram. Gas jar CO2 gas ii. Why is the gas jar kept Pieces of CaCO3 erect? iii. How can we test this gas? 23. Draw a chart to show the types of offspring produced in F1 and F2-generations after the cross-fertilization between pea plant with red flower and that with white flower. Show genotype and phenotype in the chart. Red flower is dominant. 24. What are the periods of Mesozoic and Cenozoic era? What are the main animals developed in those eras? Explain. GREEN Science (Geology and Astronomy) Book-10 429

MODEL QUESTION SET 2 All the questions are compulsory. (Group ‘A’) 15x1=15 1. Write short answers to the following questions: a. What is gravity? Write down its unit in SI system. b. State Pascal’s law and write any one equipment based on this law. c. Mention the temperature at the surface and centre of the sun. (Ans: 5700°C, 1.5 x 107°C) 1 d. What type of defect of vision is called myopia? Write. e. Which metal is used to make filament? Write its melting point. (Ans: Tungsten, 3400°C) 1 f. Give any two examples of p-block elements. 1 g. Write any two characteristics of catalyst. 1 h. What type of salt is called acidic salt ? 1 i. Write any two physical properties of copper. 1 j. What is cocoon? Write its function. 1 k. Write down the function of sympathetic nervous system. 1 l. What is systemic circulation ? 1 m. What is cross-pollination ? 1 n. Write any two causes of mutation. 1 o. Write the name of any two comets. (Ans: Enke, Bennet) 1 Group ‘B’ 13x2=26 2. Answer the following questions after observing the Load given diagram of hydraulic press. AB i. On what principle does this machine work? State the principle also. Piston ii. What role is played by water to multiply the force Water in this device? 3. A ship can carry more load than an aeroplane of the same size. Why? 2 430 GREEN Science (Geology and Astronomy) Book-10

4. Explain briefly, why there is an acute need of the search for alternative sources of energy on the earth? 2 5. Short-sightedness cannot be corrected by the use of a convex lens, why? 2 6. The atoms of elements become larger and larger when we move towards left and below a group. How does it affect the chemical reactivity of the elements? 2 7. Which type of salt is NaHSO4? Write with reason. 2 8. Aluminium is a very reactive metal. However, the foods in aluminium pots don’t react with the pots, why? 2 9. Write two differences between thermoplastic and thermosetting plastic. 2 10. What does it mean by “tapeworm reproduces by the process of regeneration”? Why is fertilization in fishes called external fertilization? 1+1 11. Valves are present in veins but not in arteries, why ? 2 12. Explain the reason that only one characteristic is found expressed in F1 generation of Mendel’s experiment. 2 13. What is meant by domestic wastes and industrial wastes ? 2 14. Describe in brief the Kant-Laplace nebular hypothesis about the origin of the earth. 2 Group ‘C’ 6x3=18 15. If an object is immersed in water, at what condition 50N ? does it float and at what condition does it sink in water? If the cross-sectional area of piston ‘A’ is 20 cm2, piston A B ‘B’ is 60 cm2 and effort of 50N is applied on ‘A’, then how much load is needed on piston ‘B’ to balance it ? 20 cm² 60 cm² (Ans: 150N) 1+2 16. Write any two utilities of concave lens. Which type of lens is shown in diagram? Calculate the power of the lens. (Ans: - 50D) 1 +2 17. Write the balanced chemical equation of the reaction that takes place when solution of sodium chloride is mixed with solution of silver nitrate. What type of reaction is this ? 3 18. Give the structural formula of ethyl alcohol and write FO F with reason whether it is saturated or not. Write one use 2 cm of this compound. 2+1 3 19. How is tip layering done? Describe with a figure. 20. Write any six measures to control air pollution. 3 GREEN Science (Geology and Astronomy) Book-10 431

Group ‘D’ 4x4=16 21. Describe in brief the working mechanism of an inverter. The number of turns in the primary winding of a certain transformer is 150 times more than that in the secondary winding. Calculate the input e.m.f. in the primary winding if the e.m.f. generated in the secondary winding is 220V AC. (Ans: 409.09 turns) 2+2 22. Study the given figure and answer the following questions. 0.5+1.5+1+1 i. Which gas is being collected Gas jar in the gas jar? Ammonium gas ii. Write this balanced chemical Mixture of NH4Cl Stand and Ca(OH)2 CaO equation involved in the Hard glass test tube process. iii. What will happen if quick Bunsen burner lime is replaced in drying tower by conc. H2SO4? iv. Name the compound formed in the gas jar if the gas jar is moist. 23. Describe the methods of conservation and management of water. 4 24. Write any four international efforts on reduction and adaptation of climate change and describe any one of them. 2+2 432 GREEN Science (Geology and Astronomy) Book-10