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Friday, 18 December 2015

CBSE Science Theory Sample paper Second Term SA 2

                                                  Science (Theory)
                                                Second Term (SA – II)
Time: 3 Hours                                                                                             M.M.: 80
                                                     SECTION-A
1. A blacksmith uses a heavy hammer and brings it from a height before striking on the chisel. Why?

2. Write the formula for kinetic energy of the object.

3. Name the two gases that comprise about 99% part of atmosphere.

4. Name any two parameters that decide which type of plants will thrive on that soil.

5. Explain the following:
(a) Swimmers are provided with an inflated rubber jacket/tube. Why?
(b) It is easier to swim in sea water than in river water. Why?

6. In a car lift, a car of 1200 kg mass is resting on a platform of surface area 10 m2.
What pressure should the platform exert on the car so as to lift it?

7. A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of sound. What is the time interval between successive compressions from  the source?

8. What are polyatomic ions? Give two examples.

9. (a) Write the electronic configuration of the elements whose atomic numbers are 5  and 7.
(b) Why is an atom considered to be neutral?

10. (a) How do gymnosperms and angiosperms differ from each other?
(b) Name the largest phylum which is probably the largest group of animals?

11. (a) List any two uses of ground water.
(b) How ozone layer is useful to us?

12. (a) Name the factors which influence the patterns of winds.
(b) Name any two green house gases.

13.(a) What is advantage of using scientific name instead of common name?
(b) Write any one point of difference between amphibians and aves.

14. (a) Distinguish between longitudinal and transverse wave. Give one example each.
(b) Write two important applications of ultra sound waves.

15.(a)Define potential energy and give few examples of objects possessing potential energy.
(b) What is gravitational potential energy? How does the change in potential energy of an object between two given points depend?

16. (a) A ship sends out ultrasound produced by transmitter that returns from the  sea bed and detected after 3.42 s. If the speed of ultrasound waves through  sea water is 1530 s-1, what is the distance of the sea bed from the ship?
(b) What is SONAR?17.a. Valencies or charges of some ions are given below:
Hydrogen ion, H+ = + 1 Oxide ion, O2- = - 2
Aluminum ion, Al3+ = 3+ Nitride ion, N3- = 3-
Calcium ion, Ca 2+ = 2+ Hydroxide ion, OH- = 1-
Sodium ion, Na+ = +1 Carbonate ion, CO2-
3 = 2-
Using the above information, write down the chemical formulae of the following:
(i) Aluminium oxide (ii) Calcium nitride
(iii) Calcium hydroxide (i) Sodium carbonate
b. Why is it not possible to see an atom with naked eyes?

18. Calculate the number of molecules of sulphur (S8) present in 16 g of solid sulphur. (Given: Atomic mass of S = 16)

19. (a) How physicians are able to pinpoint a particular disease?
(b) What is the main difference between communicable and non-communicable  diseases?

20. (a) Give suitable term for the following:
i. Animals carrying the infecting agents from a sick person to another
potential host.
ii. Preventive inoculation against a disease.
(b) Write the full form of AIDS. Name the virus that caused AIDS.

21.(a) What is the binomial system of nomenclature?
(b) Mention any two characteristic feature of phylum Echinodermata?

22.(a) Under which of the following conditions is a person most likely to fall sick?
(i) When she is recovering from malaria.
(ii)When she has recovered from malaria and is taking care of someone suffering from chicken pox.
(iii) When she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chicken-pox. Why?
(b) Name any two infectious diseases against which vaccine is available.

23. (a) What is the amount of work done:
(i) By an electron revolving in a circular orbit of radius r round a nucleus?
(ii) By an electron moving with half the speed of light in empty space free of all forces?
(b) An electric pump is used to pump water from an underground sump to the overhead tank situated 20 m above. It transfers 2000 kg of water to overhead tank in 15 minutes. Calculate the power of pump.
(c) What do you mean by instantaneous power of a device?
Or
(a) Certain force acting on a 20 kg mass changes its velocity from 5m/s to 2m/s. Calculate the work done by the force.
(b) State two possible conditions under which the work done would be zero.
(c) If the kinetic energy of the body is increased by 300% then determine the  percentage increase in the momentum.

24. (a) How is the valency of an atom related to its electronic configuration?
(b) Composition of the nuclei of two atomic species A and B is given as under: A B
Protons = 6 Protons = 6
Neutrons = 6 Neutrons = 8
Calculate the mass numbers of A and B. What is the relation between the two species  and which element or elements do they represent?
OR
(a) Why is helium inert?
(b) Why Na atom gets 1+ charge when it loses one electron?
(c) What are the limitations of Rutherford's model of the atom?
(d) Name the particles which determine the mass of an atom.

25.(a) Define water cycle.
(b) Draw water cycle in nature giving neat and labeled diagram.
(c )
i. What is nitrogen fixation?
ii. What is the effect of oxygen on nitrogen?
Or
(a) Define soil pollution.
(b) Name any two methods to prevent the loss of top soil.
(c) How is acid rain formed?



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