14 January 2012

CBSE Science and Technology Class: X Assignments 2012

CBSE Science and Technology Class: X Assignments 2012
1.Write the molecular formula of ethanol.
2.An organic compound X having molecular formula C2H4O2, gives brisk effervescence with sodium bicarbonate. Give the formula and the name of X.
3 The general formula of a homologous series of carbon compounds is CnH2n+1OH.Write the molecular formulae of fourth and fifth members of this series?
4.Illustrate the IUPAC system of nomenclature for the following compounds:
    (a).CH3OH        (b).C2H8OH           (c ).C3H7OH.
5.What happens when a dry piece of sodium metal is added to ethyl alcohol?
Explain with equation.
6.What happens when ethyl alcohol is warmed with alkaline potassium permagnate?
7.What will be the formula and electron dot structure of Propyne?
8.Write chemical equation for saponification & esterification.
9.The molecular formula C3H6O can represent an aldehyde as well as a ketone.
Write their structure and name them.
10.Why should one condemn drinking of alcohol?
11.Define isomerism.
12.How is that we can use  detergents not soaps for washing clothes even when water is hard?
Assignment Subject: Class: X Chapter: Periodic Classification of Elements

  1. How many elements were discovered at the time of Mendeleev?
  1. Define Atomic radius and give its variation along group and period.
  1. Three elements A, B and C having atomic radii 124pm, 456pm and 324pm respectively. Arrange them according to their position in group.
  1. Which law was based on the notes of music?
  1. State Modern periodic law.
  1.  What was the main advantage of Mendleev’s periodic table?
  1. What are metalloids? Explain about their position in Modern periodic table.
  1. Why was it necessary to change the basis of classification from atomic weight to atomic number?
  1. Two elements having atomic no.12 and 17 both belong to same period. State reason.
  1. Explain how Modern periodic law was able to tell about the position of isotopes in periodic table, which cannot be explained by Mendeleev?
  1. (a) State two defects of Modern periodic table.
  1. What are the units of inheritance in living organisms? Where are they located?
  1. Name the theory of evolution given by Charles Darwin & name the book in which it was given?                                              
  1. Define Genetics. What was the contribution of Mendel in this branch of biology?
  1. How do embryological studies provide evidence in favor of evolution?
  1. How is artificial selection beneficial?
  1. How analogous organs provide evidence in favor evolution?
  1. Explain diagrammatically Mendels MONOHYBRID & DIHYBRID CROSS?
  1. Humans have evolved in a tree like structure. Discuss.
  1. A cross between round and wrinkled seeds produced round seeds. When these were selfed out 420 seeds 300 were round &102 were wrinkled.
  1. A species give rise to new species with a complex body design. Will be better than the old species.
  1. A ray of light incident normally on a mirror retraces its path. Why?
  1. State mirror formula. Will focal length of mirror changes on changing the distance of the object? If not, why? What determines the focal length of the mirror?
  1. What kind of lens is there in human eye? What enables the eye to focus objects at different distances?
  1. Explain: a) Sun appears to rise 2 minutes before and sets 2 minutes later.What is meant by persistance of vision?
  1. b) Sky appears blue.
  1. c) Stars twinkle at night
  1. What is meant by myopia and hypermetropia? How can the two be corrected? Explain with the help of diagram?
  2. A person cannot see the object distinctly hen placed at a distance less than 100 cm. What is the power of spectacles that he should use to see clearly the objects placed at 25 cm?
  3. A 14-year-old student is not able to see clearly the questions written on the blackboard placed at a distance of 5m from him (a) Name the defect of vision he is suffering from. (b) With the help of labeled ray diagrams show how this defect can be corrected (c) Name the type of lens used to correct the defect.
  4. What is presbyopia? What causes presbyopia? How it can be corrected?
  1. Why we are not able to see immediately after we enter a darkened hall?

(b) The atomic number of X, Y and Z are 9, 11 and 17.
i.) Which of them belong to the same group?
ii.) Which of them belong to the same period?
iii.) Which is bigger in size: X or Z and why?
12. (a) Give reason:
i). A chlorine atom is smaller than a sodium atom although atomic number of chlorine (11) is greater than sodium (17).
ii.) All elements of the same group have similar properties.
iii.) the noble gases are placed in separate group.
(b) An element X belongs to third period and group 16 of the periodic table.
i)    Write its electronic configuration and name.
ii)   What is the valency of X?
1.What is the basic difference between asexual and sexual reproduction?
2.Which of the following organisms reproduce by asexual method? Amoeba, Cat, Birds, Hydra.
3Name one organism, each which reproduces by:
 a. Binary fission     b Spore formation        c. Budding      d. Fragmentation
4. Where are  male and female gametes formed in:
a. Human beings               b. flowering plants.
5. What is vegetative propagation? Give its two advantages.
6. Differentiate between unisexual and hermophrodite organisms.
7. Define fertilization. Where does fertilization take place in human body?
8. What are STD`s? Give 2 examples.
9. Draw labeled diagram of:  A) Human male reproduction system   b) Human female reproduction system 
10. What are male and female gonads in human beings?
11. What is pollination? Explain the 2 types of pollination.
12. Explain the structure of flower with the help of a labeled diagram.
13. Define the terms~
                a) Gestation period        b) Implantation     c) Placenta    
14. Describe the function of surgical method of birth control.
15. What is the full form of OCs? Which substances are contained in these? How do they work? 
Assignment Subject: Science and Technology Class: X Chapter: Heredity and Evolution

3. A thin lens has a focal length of –25 cm. What is the power of the lens? Is it convex or concave?
4. A converging mirror form a real image of height 4 cm, of an object of height 1 cm placed 20 cm away from the mirror. Calculate the image distance. What is the focal length of the mirror?
5. An arrow 2.5 cm high is placed at a distance of 25 cm from a diverging mirror of focal length 20 cm. Find the nature, position and size of the image formed.
6. A pond of depth 20 cm is filled with water of refractive index 4/3. Calculate apparent depth of the tank when viewed normally.
7.Calculate the distance at which an object should be placed in front of a thin convex lens of focal length 10 cm to obtain a virtual image of double its size.
8. 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
Assignment Subject: Science and Technology Class: X Chapter: Our Environment

1.Which of the following materials are biodegradable? Aluminium wire, Tea leaves, Synthetic fibre and wool.
2 Arrange the following in a food chain: Fish, Algae, Small animals and Big fish.
3.Define tropic level. Draw the food chain with four tropic level.
4.In a food chain consisting of grass, frog, bird and insects, where will the concentration of the harmful chemical be maximum?
5.What is meant by bioconcentration of pestisides? Which common pestisides has accumulated in human body in considerable amounts?
6.If we use excess pestisides to protect the crops from diseases,then it may cause long term damage to mankind.Justify the statement.
7.What is the difference between food chain food web?Give suitable examples. Explain how harmful chemicals enter our bodies.
8.What is ozone and how does it affect any ecosystem?
9. Write a note on the flow of energy through different steps in the food chain.
10.Consider the food chain: Grass-Goat-Tiger.
If tiger has 30 J of energy available in this food chain, how much energy was originally available in grass?
11.What is 10%law? Explain with an example how energy flows through different tropic levels.
Assignment Subject:Class: X Chapter: Management of Natural Resources
1.Name the three R’s to save the environment. Explain each of them.
2.What is ‘Amrita Devi Bishnoi National Award’?
3.Explain the role of forests in conserving the environment. How do forests get depleted? What are its consequences?
4.What is Narmada Bachao Andolan?
5.What are the advantages of building dams?
6.How do you achieve sustainable development?
7.How is Khejari tree related to the preservation of biodiversity?
8.How do we find contamination of water?
9.How is conservation indifferent from preservation?
10.How does socio-cultural environment affect human beings?
11.Name any two wastes that can be recycled and reused.
12.How can you as an individual contribute or make a difference to the management of:
      (a) forests and wild life.            (b)water resources       (c)coal and petroleum?


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