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(Download) CBSE Class X Science Guess Paper 2011-2012

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Guess Paper – 2012 Class – X Subject – Physics
  1. Name one physical condition on which resitivity of metal depends? 
  2. What is the resistance of an electric lamp if it uses 20A when connected to a 220 V? 
  3. Why is an ammeter likely to burn out when connected in parallel? 
  4. Define current and give its SI unit. 
  5. What is SI unit of potential? 
  6. Relate1 J and 1V. 
  7. Define resistivity and give its SI unit? 
  8. When length of a wire is doubled, what is changed in resistivity? 
  9. Write the least and maximum possible value that can be obtained when resistors of 2, 3, and 5 ohm are used. 
  10. Define electric power and give its SI unit. 
  11. What is commercial unit of electric power? 
  12. Name the material used for filament of heater. 
  13. What type of connection is used in our house wiring? 
  14. How is voltmeter connected in circuit? 
  15. Why series arrangement is is not used in house wiring?
SHORT ANSWERS


1 .Why is tungsten used for filament of bulb?

2. Why cord of a heater doesn’t glow where as its filament glow?

3. State Ohm’s law. Why its experimental verification is carried on at low voltage?

4. Define the terms, fuse, and short circuit and overloading.

5. Prove that equivalent resistance of resistors R1 , R2 , and R3 connected in parallel is given by 1/R=1/R1+1/R2=1/R3 
6. R1 , R2 & R3 are three resisters connected in series . derive equivalent resistance for circuit. If value of two resistance are 10 Ω and 20 Ω , and a current of 5A flow through circuit having p.d 12v , find value of third resistor if all 3 are connected in parallel, also draw the schematic diagram. (3 mark)
7. State and derive joule’ s law. An electric iron consumes energy at rate of 840w when heating is at maximum rate and 360 w when heating is at minimum. The voltage is 220v . what are the current and resistant in each case? (5 mark)
8. Why inert gas such as nitrogen, filled in electric filament? 
9. How many electrons are associated with (i) one coulomb of charge? (ii) The flow of current of 16 mA for 100 s? 
10. A torch bulb is rated at 3V and 600mA. Calculate it’s
a) Power b) Resistance c) Energy consumed if it is lighted for 4 Hrs. 
11. A bulb is rated at 220V- 100W. What is its resistance? Five such bulbs burn for 4 hrs. What is the energy consumed? Calculate the cost if the rate is 50paise per unit? (3 mark)
12. Two lamps rated 100W, 220V and 25W, 220V are connected in parallel to 220V supply. Calculate the total current through the circuit also find if voltage be 110V. 
13. How ammeter and voltmeter are connected in circuit also draw schematic diagram? What are the ideal resistances for these components? 
14. A battery of 9V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4 Ω,0.5 Ω and12 Ω respectively. How much current would flow through the 12 Ω resistor? 

NUMERICALS
  1. A rod has resistivity of 0.002ohm M . if its length is doubled and area is halved, what is the new resistivity? 
  2. A 100W electric bulb is lighted for 2 hrs daily and four 40W bulbs are lighted for 4 hrs per day. Calculate the cost of electric bills @ Rs 4 / unit. 
  3. A piece of wire having resistance R is cut into 4 equal parts. Compare resistance of each part to total equivalent resistance, if these are connected in parallel. 
  4. A copper wire has diameter 0.5mm and resistivity of 1.6ohm cm . How much long wire will needed to make a coil of 10 ohm resistance? 
  5. A resistance of 4 ohm and a bulb of resistance 20 ohm is connected in series. find a. Total resistance of circuit. b. current through bulb c. potential difference across bulb
Subject – Biology
Q. 1.CHOOSE THE CORRECT OPTION (MCQs) (1marks each )
i) Genetic Material Is 
a) RNA b) DNA c) ATP d) NADP 
ii) Regeneration Takes Place In 
a) Earthworm b) Hydra c) Amoeba d) Planaria 
iii) Future Shoot Originate From 
a) Plumule b) Radicle c) Seed Leaf d) Seed Coat 
iv) Contraceptive Devices Which Acts By Changing Hormonal Change 
a) Condoms b) Copper-T c) Pills d) Surgical Method 
v) Weeping Of Uterus Is 
a) Menstruation b) Periods c) Both d) None 
Q. 2. Define (1) each 
i) Fragmentation ii) Budding  iii) Endospore iv) Thalamus v) Pollination 

-------------------------Section-B------------------------- 

Q. 3. Answer these following (2) each 

i) What is double fertilization? Write its significance. 

ii) Draw a well labeled diagram of flower showing its vertical section. 

Q. 4 Answer these following (3) each 

i) Define fission. How binary and multiple fission differs? 

ii) What is variation? Discuss its importance. 

-------------------------Section-C------------------------- 

Q. 5. i) What is reproduction? How do complex organisms reproduce? 

ii) Write advantages of sexual reproduction over asexual reproduction. 

iii) Expand the following a) AIDS B) HIV C) STDs d) NADP _________ (2+2+1=5) 

Subject – Chemistry
Very short answers

1. What is molecular formula of bleaching powder?

2. What effects does the concentration of H+ (aq) have on the acidic nature of the solution?

3. Why should curd and sour substances should not be kept in brass or copper vessel?

4. Name the substance which on treatment with chlorine yields bleaching powder?

5. Write equation between plaster of Paris and water.

6. A solution reacts with crushed egg shell to give a gas that turns lime water milky. The solution contains,

a. NaCl b. HCl c.LiCl .c. KCl

7. A solution turns red litmus blue, its PH is likely to be,

a. 1 b. 4 c. 5 d. 10

8. What are indicators?

9. Which acid is present in curd?

10. What is aqua –regia?

11. What is colour of phenolphthalein in dil HCl?

12. Which gas is evolved when zinc granules react with dil. H2SO4?

13. Why does not react with Dil. H2SO4?

14. Which acid is present in vinegar?

15. Name one natural indicator.

Short answers (2 or 3 marks)
Write formula of ,

a. nitric acid b. carbonic acid c. acetic acid . d. formic acid

2. What role does water play in litmus test?

3. Write PH of acid rain and blood?

4. What happen when copper oxides react with HCl? Give chemical reaction.

5. What is milk of magnesia? Give its use.

6. What happen when copper metal is added to silver nitrate solution?

7. Which gas is usually liberated when an acid react with metals?

8. Why does distilled water doesn’t conduct electric current where as rain water does?

9. Why plaster of Paris should be stored in moisture proof container?

10. Equal length of magnesium ribbon are taken in test tube ‘A’ and ‘B’. HCl is added to A and CH3COOH is added to B. In which test tube will the fizzing occur more vigorously and why?

11. Why baking soda is used in making cakes?

12. Give three uses of bleaching powder.

13. Give two role of acid in every day life.

14. What is neutralization reaction? Illustrate with one example.

15. What will be products if acids react with?
a. Metals   b. Metal hydrogen carbonates  , Illustrate with equations.
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