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Q.1: Find the surface area of a cuboid which is 16.4 m long , 15.5 m broad and 8.5m high.
Q.2: A chalk box is in the form of a cube of edge 10.5cm.Find its surface area. Q.3: Find the lateral surface area of a right circular cylinder whose height is 13.5cm and radius of the base is 7cm.Find also its whole surface area. Q.4: A roller 150cm long has a diameter of 70 cm.To level a playground it takes 750 complete revolutions .Determine the cost of levelling the playground at the rate of 75 paise per sq. metre. Q.5: Find the diameter of a sphere whose surface is 346.5sq.cm. Q.6: A conical tent is 10m high and the radius of its base is 24m.Find its slant height.Also find the cost of canvas used in making the tent at Rs. 70 per sq.m. Q.7: A hemispherical bowl is made of steel 0.25cm thick .The inner radius of the bowl is 5cm .Find the outer curved surface area of the bowl. Q.8: Find the volume of a cuboid whose length is 16.4m, breadth =15.5m and height =8.5m. Q.9: A river 3m deep and 40m wide is flowing at the rate of 2km per hour .How much water will fall into the sea in a minute? Q.10 The volume of a right circular cylinder is 1100cu cm and the radius of its base is 5cm.Find its curved surface area. Q.11: A cubodal vessel is 10m long and 8 m wide.How high must be made to hold 380 cu m of a liquid. Q.12: Find the capacity in litres of a conical vessel whose diameter is 14 cm and slant height 25cm. Q.13: What are the cubical contents of a well whose diameter is 42 dm and depth 150 dm.? Q.14: The circumference of the base of a cylindrical vessel is 132 cm and its height is 25 cm .How many litres of water can it hold? [1000cu cm=1litre] Q.15: A heap of wheat in the form of cone whose diameter is 10.5m and height 3m .Find its volume. The heap is to be covered by canvas to protect it from rain. Find the area of canvas required. Q.16: The diameter of the moon is approximately one-fourth of the diameter of the earth .What fraction of the earth is the volume of the moon? Q.17: The radius of a sphere is 5cm .f the radius be increased by 20% ,find by how much %age the volume is increased. Q.18: A gowdown measures 40mx25mx10m.Find the maximum number of wooden crates each measuring 1.5m x 1.25m x 0.5m that can be stored in the gowdown. Q.19: Find the length of the longest rod that can be placed in a room 12mx9mx8m. Q.20: A 4cm cube is cut into 1cm cubes .Calculate the total surface area of small cubes. What is the ratio of surface area of small cubes to that of the large cube? Q.21: A field is 60m long and 20m wide.A tank 12m long ,10m broad and 3m deep is dug in the field .The earth taken out of it is spread evenly over the field .How much is the level of the field raised supposing the earth taken out increases by 1/8 of the volume? Q.22: A village having a population of 4000, requires 150 litres of water per head per day . It has a tank measuring 20m x 15m x 6m.For how many days will the water of this tank last ? Q.23: It costs Rs. 2200 to paint the inner curved surface of a cylindrical vessel 10m deep .If the cost of painting is at the rate of Rs. 20 per sq.m, find (i) inner curved surface area of the vessel (ii) radius of the base (iii) capacity of the vessel Q.24: The radius and height of a right circular cone are in the ratio 5:12. If its volume is 314 cu cm, find its slant height. ( take π=3.14) Q.25: A rectangular water reservoir is 7.2m by 2.5m at the base . Water flows into it through a pipe whose cross section is 5cm x 3cm at the rate of 10m per second .Find the height to which the water will rise in the reservoirs in 40 minutes.  1. An object is placed between two plane mirrors inclined at an angle of 45° to each other. How many images do you expect to see?
2. A convex mirror is held in water. What should be the change in its focal length? 3. If the light from the Sun subtend an angle Q at the pole of a concave mirror of focal length f, where will it converge? Also find the diameter of the image. Draw the necessary ray diagram. 4. When does Snell’s law of refraction fail? 5. How does the frequency of a beam of ultraviolet light changes when it goes from air to glass? 6. State two conditions under which a ray of light suffering refraction from medium 1 to medium 2 does not undergo any change in direction 7. Name the factor on which lateral shift produced by glass slab depends? 8. A glass lens is immersed in water. How is the power of the lens affected? 9. Why is the power of a lens is measured as reciprocal of focal length? Give reason. 10. A convex lens is made of a material of refractive index m1 when placed in a medium of refractive index m2, behaves as a diverging lens. How are m1 and m2 related? 11. An object is held at a distance of 60 cm from a convex mirror of focal length 20 cm. At what distance from the mirror, should a plane mirror be held so that images in the two mirrors coincide?(ans. 22.5 cm) 12. How do you find the rough focal length of a convex lens? Is the same method applicable to a concave lens? 13. Which factors determine the focal length of a lens? 14. The formula for linear magnification of a spherical mirror is m=h’/h = -v/u. What determines the sign of m? What is the significance of this sign? 15. A convex lens made of material of refractive index n2 is kept in a medium of refractive index n1. A parallel beam of light is incident on the lens. Compare the path of rays of light emerging from the convex lens if (i)n1<n2 (ii)n1=n2 (iii) n1>n2 16. A concave lens of focal length 25 cm and a convex lens of focal length 20 cm are placed in contact with each other. What is the power of this combination? Also, calculate focal length of this combination. (ans. 1m) 17. A convergent lens of power 8D is combined with a divergent lens of power -10 D. Calculate focal length of the combination. (ans.-0.5 m) 18. A concave lens has a focal length of 15 cm. At what distance should an object from the lens be placed so that it forms an image at 10 cm from the lens? Also find the magnification of the lens. 19. Under what condition in an arrangement of two plane mirrors, incident ray and reflected ray will always be parallel to each other, whatever be the angle of incidence? Show the same with the help of diagram. 20. How much time will light take to cross 2 mm thick glass pane if refractive index of glass is 3/2? (ans. 10-11s) 21. Light travel from rarer medium 1 to a denser medium 2. The angle of incidence and refraction are respectively 45° and 30°. Calculate the refractive index of second medium with respect to the first medium. 22. A pond of depth 20 cm is filled with water of refractive index 4/3. Calculate apparent depth of the tank when viewed normally. 23. Light of wavelength 500nm in air enters a glass plate of refractive index 1.5. Find (a)speed. (b)frequency, and (c)wavelength of light in glass. Assume that the frequency of light remains the same in both media. 24. A myopic person prefers to remove his spectacles while reading a book. Give reason. 25.A hypermetropic person prefers to remove his spectacles while driving a vehicle. Give reason Solution: Light Refraction and Refraction solved questions-5 Download File  Class 10th (SA-II), Session:2012-13 Chemistry Assignment- IV
Chapter :(carbon and its compounds) 1. An organic compound X with a molecular formula C2H6O undergoes oxidation with in presence of alkaline KMnO4 to form a compound Y. X on heating in presence of Conc. H2SO4 at 443K gives Z. Which on reaction with H2Oin presence of H2SO4 gives back `X` `Z` reacts with Br2 (aq) and decolorizes it. Identify X, Y, & Z and write the reactions involved. 2. An organic compound ‘A’ is widely used as a preservative in pickles and has a molecular formula C2H2O2. This compound reacts with ethanol to form a sweet smelling compound ‘B’. (i) Identify the compound ‘A’ (ii) Write the chemical equation for its reaction with ethanol to form compound ‘B’. (iii) How can we get compound ‘A’ back from ‘B’? (iv) Name the process and write corresponding chemical equation. (v) Which gas is produced when compound ‘A’ reacts with washing soda? Write the chemical equation. 3. Hydrocarbon `X` and `Y` having molecular formulae C3H8 and C3H6 respectively. Both are burnt in different spatula on the Bunsen flame. Indicate the color of the flame produced by `X` and `Y`. Identify `X` and `Y`. Write the structural formulae. 4. A compound `X` has molecular formula C4H10. It undergoes substitution reaction readily than addition reaction. It burns with blue flame and is present in LPG. Identify `X` and give the balanced equation for its combustion and substitution reaction with Cl2 in presence of sunlight. 5. `A` compound works well with hard water. It is used for making shampoos & products for cleaning clothes. A is not 100% biodegradable and causes water pollution. `B` does not work well with hard water. It is 100% biodegradable and does not create water pollution. Identify A & B. 6. An organic compound P with molecular formula C2H6Ois an active ingredient of all alcoholic drinks. It is also used in medicines such as tincture iodine, cough syrups. Identify `P`. Drop a small piece of sodium into the test tube containing `P`.A new compound `Q` is formed with the evaluation of colorless and odorless gas Name the gas evolved and compound `Q` write the chemical reaction. 7. A cyclic compound `X` has molecular formula C6H6. It is unsaturated and burns with sooty flame. Identify `X` and write its structural formula. Will it decolorize bromine water or not and why? 8. An organic compounds `A` is a constituent of antifreeze and has the molecular formula C2H6O upon reaction with alkaline KMnO4, the compound `A` is oxidized to another `B` with formula C2H6O2. Identify the compound A` and `B`. Write the chemical equation for the reaction which leads to the formulation of `B` 9. Two compounds `X` and `Y` have the same formula C2H4O2. One of them reacts with sodium metal to liberate H2 and CO2 with NaHCO3. Second one does not reacts with Na metal and NaHCO3 but undergo hydrolysis with NaOH to form salt of carboxylic acid and compound `Z` which is called wood spirit. Identify `X`, `Y`, and `Z` and write chemical equation for the reaction involved. 10. A compound `X` with molecular formula C2H4 burns with a sooty flame. It decolourise bromine water. Identify `X`. Will it dissolve in water or not? Will it conduct electricity in aq. Solution? Will it have high melting point or low melting point? 11. Write the formula for ‘ethanoic acid’ and name the functional group present in it. 12. Allotropy is a property shown by which class: - Substances, elements, compounds, mixture. 13. What is the use of oxyacetylene flame? 14. Name the gas which is formed by decomposition of plants and animal matter in marshy areas? 15. Mention the name of the byproduct of soap industry. 16. Write the molecular formula and structures of benzene. 17. Match the following:- 1. Ethane - Used in anti freeze solution. 2. Ethanol - fruity smell. 3. Ester - fossil fuel. 18. Write two uses of fullerenes. 19. Complete and balance following equation:- a) CH2=CH2 + H2 heat, Ni b) CH4+O2 20. Two alkanes A and B have 4 and 6 carbon atoms respectively in their molecule. In which physical state will they occur at room temp? 21. Give a test that can be used to differentiate chemically between butter and cooking oil. 22. How will you distinguish between ethanol and ethanoic acid by a suitable chemical test? Write chemical reactions involved. 23. Complete the following reactions:- 1) CH3COOH + NaHCO3 conc.H2SO4 2) HCOOH + CH3OH 3) CH3COOC2H5 + H2O 24. Name the compound CH3COOC2H5.Name the acid and alcohol from which it is made, write equation. http://www.davblb.ac.in/assignments.asp What is environment?
The sum total of all surroundings of a living organism, including natural forces and other living things, which provide conditions for development and growth as well as of danger and damage is called environment. What happens when we add our waste to the environment or throw ? When we add our waste to the environment some of them are broken down by the biological processes but rest persists for a long time. What are the different types of waste materials? Waste that are broken down by the biological processes are said to be biodegradable. These wastes are decomposed through the actions of fungi, bacteria and other living organisms and enrich soil fertility. Examples: Food refuse, tree leaves urine and faecal matter, ewage agricultural residue, paper, wood, cloth, cow-dung, etc Waste that are not broken down by the biological processes are said to be non biodegradable. These substances are inert and simply persist in the environment for a long time or may harm the various members of the ecosystem. Example ; these includes DDT, insecticides, pesticides, mercury, lead, arsenic, aluminimum, plastics, polythene bags, glass, radioactive wastes. What happens after we throw waste away them away? Fungi, bacteria and other living organisms in the presence of temperature and sunlight act on waste and try to break down. Why are some substances biodegradable and some non-biodegradable? Some substances are biodegradable and some are non bio-degradable. This is because of the specific action of the enzymes produced by bacteria or decomposers. The enzymes can break down natural substances into non poisonous simpler substances but cannot act on man-made substances like plastics What are the harmful effects of biodegradable substance? 1. This waste destroyed the natural beauty and surroundings become dirty. 2. Decomposition of these wastes results in the production of foul smell, which spreads to surroundings areas. 3. These wastes may also block the drains creating pools of waste which becomes the breeding sites of mosquitoes. The letter is carriers of diseases like malaria and dengue. What are the harmful effects of non- biodegradable substance? 1. These wastes are very harmful. They enter the food chains and their concentration goes on increasing from one trophic level to the next. This leads to biological magnification and result in harmful effects in human beings and other animals. 2. Dumping these wastes affects the soil fertility and subsequently reduces the crop yield. 3. Non-biodegradable chock out the sewage system and pollute the soil. 4. Some of the non-biodegradable substances may toxic for the humans and produce various diseases. Name some of the biodegradable plastics. Polyhydroxyalkanoates (PHAs) like the poly-3-hydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxyhexanoate (PHH) . What are the differences between biodegradable and non-biodegradable wastes. Biodegradable Wastes 1. The wastes are broken down naturally by microbial action 2. Biodegradation forms harmless and nonpoisonous products. 3. They release raw materials back to nature. 4. They pollute the environment only when they are produced in quantity beyond the capacity of environment to degrade them. 5. Recycling is possible either naturally or through human efforts. Non-biodegradable 1. The wastes are not broken down by the microbes. 2. No such action is possible. 3. They do not release raw materials. 4. Non-biodegradable wastes pollute the environment even in small quantity. 5. Recycling is possible only through human efforts. What is echo system? Ecosystem is a structural and functional unit of the biosphere consisting of a community of living beings and the physical environment. For example: forests, ponds and lakes are natural ecosystems while gardens and crop-fields and aquarium are human made (Artificial) ecosystems. What are the different types of echo system? Natural ecosystems are grass land, a forest, a sea, a river, a desert, a mountain, a pond, a lake etc. The desert, grass land and mountain represent the terrestrial ecosystem (land based ecosystem). The ponds, rivers, lakes and sea represent the aquatic ecosystem (water- based ecosystem). Man – made or artificial ecosystems are garden, crop fields, park aquarium, etc. Why does aquarium have to be cleaned once in a while? To remove fish wastes from the water because there are no bacteria and fungi to break-down the dead remains and waste products of organisms. --------------==================================--------------------- 10th Science - Our Environment: Summative assignments View/Read 10th Chapter: Our Environment Questions Paper for FA-III View/Read 10th Science: Chapter: Our Environment HOTS Questions View/Read 10th Chapter: Our Environment: Gist of Lesson View/Read 10th Our Environment CBSE SOLVED GUESS PAPER Download Gist of Lesson for Quick Revision (By JSUNIL)
1. An eye is the most important organ of the human body. It is associated with vision and acts as a vital optical instrument. 2. An eye is spherical in shape of about 2.3 cm diameter and is covered externally by a hard thick and opaque layer called Sclerotica. The outermost layer of the eye is sclerotic that prtects and holds the eye. 3. Cornea is transparent part bulging out of eye and allows the light to enter in the eye. Cornea is also known as the window or aperture of the eye. 4. Iris is a circular diaphragm having a hole in its center .this hole is called pupil 5. Iris has muscles and coloured pigments that provide different colour y eyes 6. Iris controls the amount of light entering the eye through the pupil. 7. The pupil becomes small when bright light falls on the eye. However, it becomes wide when there is dim light. 8. The eye lens is a crystalline convex lens made up of transparent and flexible tissues behind the pupil and held by the muscles called ciliary muscles. It focuses inverted the images of objects on the retina of the eye. 9. Ciliary muscles control the focal length of the eye lens by contracting and relaxing. This ability 10. When ciliary muscles contract lens become thin thus the focal length of the lens increases. 11. When ciliary muscles expand lens become thick, and decrease the focal length of the lens. This helps us to see nearby objects clearly. 12. The ability of the eye lens to adjust its focal length is called accommodation. 13. The focal length of the eye lens cannot be decreased below a certain minimum limit this is why a normal eye not able to see clearly the objects placed closer than 25 cm. 14. The image distance in the eye remains same when we increase the distance of an object from the eye as distance between eye lens and retina is constant. 15. The least distance of distinct vision for a young adult with normal vision is about 25 m. it is called near point 16. The furthest distance of distinct vision for a young adult with normal vision is at infinity. it is called far point. 17. The human eye can focus objects at different distances by adjusting the focal length of the eye lens. This is due to accommodation. 18. A normal eye can see objects clearly that are between 25 cm and infinity. 19. In old age eye lens of people becomes milky and cloudy. This condition is called cataract. This causes partial or complete loss of vision. It is possible to restore vision through a cataract surgery. 20. One eyes of human being has a horizontal field of view of about 150° So for a horizontal field of view of about 150° 180° We have two eyes. Read more » SUMMATIVE ASSESSMENT – II
Time: 3 Hrs Max. Marks: 90 General Instructions: i) The question paper comprises of two sections, A & B. You are to attempt both the sections. ii) All the questions are compulsory. iii) There is no overall choice. However, internal choice has been provided in all the five questions of five marks category. Only one option in each question is to be attempted. iv)All the questions of Section A and all sections of section B are to be attempted separately. v) Question numbers 1 to 3 in Section A are 1 mark questions. These are to be answered in one word or one sentence. vi) Question numbers 4 to 7 are 2 mark questions, to be answered in about 30 words. vii)Question numbers 8 to 19 are 3 mark questions, to be answered in about 50 words. viii) Question numbers 20 to 24 are 5 mark questions, to be answered in about 70 words. ix)Question numbers 25 to 42 is Section B are Multiple Choice Questions on Practical Skills. Each question is 1 mark question. You are to choose one most appropriate response of the options provided to you. Section-A Q.1 List the three phenomenon of light responsible for formation of rainbow in the sky. Q.2 Why is DNA copying an essential part of the process of reproduction? Q.3 List any two common methods by which solid wastes of urban areas are disposed off. Q.4 Why do we see stars twinkling whereas, where as planets do not twinkle? Q.5 (i) What is meant by ‘power of accommodation of the eye’? (ii) How does the focal length of the eye lens change when we shift looking from a distant object to a nearby object? Q.6 (i)Why are Coal and petroleum called fossil fuels? (ii) Name the two elements which are present both in CNG and Petroleum? Q.7 (i) What is the position of hydrogen in the model periodic table? (ii) Where are isotopes of the same element having different atomic masses placed in the periodic table? Q.8 Pure- breed pea plants A are crossed with pure breed pea plants B. It is found that the plants who look like A do not appear in F1 generation but B re-emerge in F2 generation. Which of the plants A and B: (i) tall,(ii) dwarf ? Give reason for your answer. Q.9 A student sitting in the last row of the classroom is not able to read clearly the writing on the Blackboard: (a) Name the type of defect of vision he is suffering from (b) How can this defect be corrected ? Q.10 (a) Name the compounds CH3COOH and identify its functional group. (b) Give a chemical test to identify this compound. (c) Name the gas evolved when this compound acts on solid carbonate. How would you identify this gas. Q.11(a) Explain the terms (i)Implantation (ii)Placenta (b) What is the average duration of human pregnancy? (c) What happens when the egg is not fertilized? Q.12(a) A spherical mirror A forms an erect image of an object, a spherical mirror B forms erect as well as inverted image of an object. Name the types of the spherical mirror A and B. (b) What is the relation between the focal length and radius of curvature of a spherical mirror? If the radius of a curvature of a spherical Mirror is 25 cm, what is the focal length? Q.13 An organic compound ‘A’ is an essential constituent of wine and beer. Oxidation of ‘A’ yields An organic acid ‘B’ which is present in vinegar. Name the compounds ‘A’ and ‘B’ and write their structural formula. What happens when ‘A’ and ‘B’ react in the presence of an acid Catalyst? Write the chemical equation for the reaction. Q.14 which of the following are homologous and which are the analogous? Give reasons 1. Trunk of the elephant and hand of a chimpanzee 2. Wing of a bird and wing of a bat. 3. Scales of fishes and shell of molluscs. Q.15 Iit is desired to obtain an erect image of an object, using an concave mirror of focal length 20cm. (i) What should be the range of the distance of object from the mirror? (ii) Will the image be bigger or smaller than the object? (iii) Draw a ray diagram to show the image formation in this case. Q.16 ( a) Why does carbon form largest number of compounds? (b) Why are some of these called saturated and other unsaturated compounds? (c) Which of these is more reactive? Q.17Write three advantages of constructing dams across the rivers? Q.18 (a) State two effects produced by scattering of light by the atmosphere? (b)Why are ‘danger’ signal lights red in colour? (c)What would the sky look like if the earth had no atmosphere? Q.19The electronic configuration of these elements X, Y and Z are given below? X 2 Y 2,6 Z 2,8,2 i)Which element belongs to second period ? ii) Which element belongs to second group? iii) Which element belongs to 18th group ? Q.20 (a) What are the main reasons why human beings are over-exploiting the forests? (b)What are the effects of damages? (c)Names the different measures taken up for the conservation of forests? Q.21:a)Why do we classify elements ? b) What were the two criteria used by Mendeleev in creating his periodic table? c) In Mendeleev’s periodic table, why was there no mention of noble gasses like helium, neon and argon? d) Why did Mendeleev leave some gaps in his periodic table? e) Would you place the two isotopes of chlorine, Cl-35 in different slot because of their different atomic masses or in the same slot because their chemical properties are the same ? Justify your answer. Q.22 Names the type of mirror (s) that should be used to obtain: (a)A magnified and virtual image (b)A diminished and virtual image of an object . ( c ) Draw labelled ray diagrams to show the formation of the required image in each of the above two cases .Which of these mirrors could also form a magnified and real image of the object ? State the position of object for which this could happen. Q.23 a) Define homologous series of organic compounds. Mention any two characteristics of homologous series. b) Name the compound formed on heating ethanol at 443k with excess of conc.H2SO4. c) Describe a chemical test to distinguish between ethanol and ethanoic acid. Q.24 (a) Give an example of bisexual flower. What is its female reproductive part known as? (b) Draw a diagram of its longitudinal section showing the process of germination of pollen on stigma and label the following on it : (c)Pollination may occur without fertilization but fertilization will not take place without pollination. Give reason . SECTION –B Q.25. an iron nail was suspended in copper sulphate solution and kept for a while. The solution a) remained blue and a coating was formed on the nail b) turned green and a coating was formed on the nail c) remained blue and no coating was formed on the nail d) turned green and no coating was formed on the nail Q.26. A student put a big iron nail each in 4 test-tube containing solutions of zinc sulphate, aluminum sulphate, copper sulphate, and iron sulphate. A reddish brown coating was observed only on the surface of iron nail which was put in the solution a) Zinc sulphate b) iron sulphate c) Copper sulphate c) aluminum sulphate Q.27. Four test tubes were taken and marked as A, B, C & D respectively. 2mL od solution of Al2(SO4)3in water was filled din each of the test tubes. Clean piece of metal zinc was placed in A, clean iron nail in B, clean copper wire in C & a clean aluminium wire in D. It was observed that no change occurred in any of the test tubes. The correct inference drawn is: (a) Zinc is more reactive than Aluminium (b) Zinc is more reactive than Copper (c) Copper is more reactive than Aluminium (d) Zinc, Iron & copper is more reactive than Aluminium Q.28. Which of the following reagents gives brisk effervescence with Ethanoic Acid? (a) Calcium Hydroxide (b) Sodium Chloride (c) Sodium Bicarbonate (d) Ammonium Chloride Q.29. A student soaked 5g of raisins in beaker A containing 25ml of ice chilled water and another 5g of raisins in beaker B containing 25ml of tap water at room temperature. After one hour, the student observed that (a) water absorbed by raisins in beaker A was more than that absorbed by raisins in beaker B (b) water absorbed by raisins in beaker B was more than that absorbed by raisins in beaker A (c) the amount of water absorbed by the raisins of both beakers A and B was equal. (d) No water was absorbed by raisins in either of the beakers A and B Q.30. When a stopper of a bottle containing a colourless liquid was removed, the bottle gave out a smell like that of vinegar. The liquid in the bottle could be a) Hydrochloric acid solution b) sodium hydroxide solution c) Acetic acid d) saturated sodium bicarbonate Q.31. In amoeba, asexual reproduction by multiple fission a) never take place b) sometimes takes place c) take place when amoeba wishes d) take place during unfavorable environment conditions Q.32.For determining the percentage of water absorbed by raisins in a given time, apart from water, raisins and a watch, we shall also require (a) a beaker, a graduated cylinder, a thermometer ,a filter paper. (b) a watch glass, a graduated cylinder, a thermometer, a weighing balance. (c) a beaker, a thermometer, a filter paper, a weighing balance. (d) a graduated cylinder, a thermometer, a weighing balance. Q.33. The inner surface of a stainless steel spoon behaves as__________. (a) concave mirror. (b) convex mirror. (c) plane mirror (d) neither concave nor convex Q.34. A student obtains a blurred image of an object on a screen by using a concave mirror. In order to obtain a sharp image on the screen, he will have to shift the mirror (a) towards the screen (b) away from screen (c) either towards or away from screen, depending upon the position of the object (d) to a position very far away from the screen Q.35. In an experiment to determine the focal length of a convex lens, a student obtained a sharp inverted image of a distant tree on the screen behind the lens. She then removed the screen and looked through the lens in the direction of the object. She will see (a) an inverted image of the tree at the focus of the lens (b) no image as the screen has been removed (c) a blurred image on the wall of the lab (d) an erect image of the tree on the lens Q.36. A student is to find the focal length of a (i) concave mirror, (ii) convex lens by using a distant object. He will observe that the screen is on the same side as the object (a) in both cases (b) in neither of the two cases (c) in case(i) but not in case(ii) (d) in case (ii) but not in case(i) Q.37. A student suggested the following Guidelines to his friend for doing the experiment on dressing the path of a ray of a light, passing through a rectangular slab, for three different angles of incidence: A) Draw outline of the glass slab at three positions on the drawing sheet. B) Draw normal on the top side of these outlines near their left end C) Draw the incident rays on the three outlines in direction, making angles of 30o, 45o, 60o with the normal drawn D) Fix two pins vertically on each of these incident rays at two points nearly 1 cm apart. E) Look for the images of the feet of these pins while fixing two pins, from other side, to get the refracted ray When he showed these guidelines to his teacher, the teacher told him that two of them need to be corrected and modified. These two Guidelines are (a) B & C (b) C & D (c) D & E (d) B & D Q.38. If you find the focal length of a concave and convex mirror respectively which appears to be the same say 20cm. If you face the mirror to distant object, then the size of the image will be (a) same in both the mirrors. (b) smaller in concave mirror (c) bigger in convex mirror (d) bigger in concave mirror Q. 39. Which one of the following is depicted in the sketch of a slide shown below? (a) Binary fission in yeast (b) Budding in yeast (c) Binary fission in amoeba (d) Budding in amoeba Q.40. which one out of the following diagrams correctly depicts an amoebas Undergoing binary fission? (a) I (b) II (c) III (d) IV Q.41. Acetic acid is: (a) Colourless, pungent smelling liquid (b) Colourless, sweet smelling liquid (c) Green coloured liquid having pungent smell (d) none of the above Q.42. If the object is at 2F of a convex lens, and then the image is at: (a) 2F (b) F (c) infinity (d) Between F and 2F 1. Periodic table: The table which classifies all the known elements on the basis of their properties in such a way that elements with similar properties are grouped together.
The first classification of elements was as metals and non-metals. This served only limited purpose mainly because of two reasons: (i). All the elements were grouped in to these two classes only. The groupcontaining metals was very big. (ii) Some elements showed properties of both-metals and non-metals and they could not be placed in any of the two classes. 2. All earlier attempts on the classification of the elements were based on their atomic weights. 3. The first attempt towards the classification of elements was made by Johann Dobereiner, a German chemist in 1829. He made sets of three elements which showed similar chemical properties and he called it triads. 4. The Triad was approximately the mean of the atomic weights of the other two members and the properties of the middle element were in between those of the other two members. 5. The average of the atomic masses of Li and K =1/2(7+39 )= 23 (Na) 5. The major drawback of Dobereiner classification was that the concept of triads could be applied to limited number of elements. It was also possible to group quite dissimilar elements into triads. 6. Lithium, Sodium, Potassium are called Alkalies metal as they react with metal and form alkalies (Caustic solution) 7. Calcium, Strontium, Bromine are called Alkalies Earth metal as they react with metal and form salt . as their oxide are alkalies in nature and exist in the Earth 8. Chlorine, Bromine, Iodine are called Halogen as their oxide are alkalies in nature and existin the Earth 9. In 1864 John Alexander Newland, an English chemist noticed that “when elements are arranged in the increasing order of their atomic masses. He found that "every eighth element had properties similar to the first element.” 10. Newland called this as the Law of Octaves due to its similarity with musical notes .For Solved CBSE Exam questions Visit JSUNILTUTORIAL Blog post by CBSE ADA 10th Chemistry Term 02 10th Periodic Classification of Elements (13 posts by Chemistry adda) 1. Construct a quadrilateral ABCD in which AB = 4.4 cm, BC = 4 cm, CD = 6.4 cm, DA = 3.8 cm and BD = 6.6 cm
2. Construct a rhombus with side 6 cm and one diagonal 8 cm. Measure the other diagonal. 3. Construct a quadrilateral PQRS in which QR = 4cm, RP = 5.6 cm, PS = 4.5 cm, RS = 5cm and QS = 6.5 cm 4. Construct a quadrilateral PQRS where PQ = 3.5 cm, QR = 6.5 cm, < P = < R = 105= and < S = 75 deg. 5.Construct a rectangle WXYZ in which WX = 7cm and XY = 4cm. 6. Construct a rhombus ABCD where AB = 4cm and AC = 6cm. 7. Construct a square ABCD where AB = 6cm. 8. Construct a parallelogram PQRS in which PQ = 4.5 cm, QR = 5.1cm and <Q=70 9.Construct a square of diagonal 6 cm long. 10 Construct a parallelogram ABCD in which AC = 3.8 cm, BD = 4.6 cm and the angle between AC and BD is 60 11. Construct a parallelogram ABCD in which AB=6.5 AC=3.8 and the altitude AL from A is 2.5cm draw an altitude from C For further study visit: Ch:Practical Geometry Multiple choice questions
1. The reason for excessive generation of waste is (a) use & throw policy (b) increased availability of food (b) non utilisation of all components of food (d) increased construction 2. Carnivores represent (a) primary consumers (b) secondary & tertiary consumers (c) Producers (d) autotrophs 3. Amount of energy transferred from one trophic level to the next is (a) 1.5% (b) 15% (c) 90 % (d)10% 4. Which of the following is present in maximum number in an ecosystem (a) herbivores (b) carnivores (c) producers (d) omnivores 5. Organisation involved in formulating programmes for protecting nvironment (a) UNEP (b) WHO (c) UNICEF (c) UNCTAD 6. A food chain always starts with (a) respiration (b) photosynthesis (c) nitrogen fixation (d) decay 7. The second trophic level is always of (a) herbivore (b) omnivore (c) carnivore (d) producer 8. In a forest ecosystem green plants are (a) primary consumers (b) primary producers (c) decomposers (d) heterotrophy 9. A food chain consists of (a) producers & primary consumers (b) producers, herbivores & carnivores (c) producers, consumers & decomposers (d) producers , carnivores & decomposers 10. The driving force of an ecosystem (a) biochemicals (b) biomass (c) solar energy (d) green plants You might also like: 10th Science - Our Environment: Summative assignments View/Read 10th Chapter: Our Environment Questions Paper for FA-III View/Read 10th Science: Chapter: Our Environment HOTS Questions View/Read 10th Chapter: Our Environment: Gist of Lesson View/Read 10th Our Environment CBSE SOLVED GUESS PAPER Download |
