CBSE Science Practice Paper Set IV

Section - A

1. Write the nature of image formed by a plane mirror. 1


2. Give one example of fast reaction. 1


3. What do you mean by conventional current flow ? 1


4. What is meant by esterification ? 1


5. In what form does heat get transmitted in solar energy ? 1


6. Express the average rate of reaction in terms of reactants and products for the following reaction : H2(g) + l2(g) ——>2HI(g). 2


7. Name the products we get when a-particle hits a nitrogen nuclei.


OR

Complete the reaction giving reason :
7N14 + 2He4 ——>……….+ 1H1 2


8. What is persistence of vision ? How does this help in motion-picture projection ? 2


9. Define the term ‘fuel1. What are primary and secondary fuels. ? To which classes of fuel do the following fuels belong :Coke, Wood, Petroleum, LPG. 2


10. Define the term electrolysis. Mention two uses in real life. 2


11. What happens when lime stone is heated strongly ? Write the chemical equation. Give one use of lime stone. 3


12. What is Nuclear fusion ? Explain with an example. 3


13. Name the alloys which are used for following purpose, Give their composition :
(i) for soldering joints
(ii) for making windows and door fittings
(iii) for making equipment for feed and diary industry
(iv) for making air crafts and kitchen ware. 3


14. Define the following :
(i) Launch vehicle,
(ii) Polar orbits,
(iii) Geostationary orbit. 3


15. Draw a neat labelled diagram of a box-type solar cooker. Give reason for the use of black surface and reflector. 

OR

Give reasons for the following events :
(0 Twinkling of stars, (ii) Mirage. 3
Answer : 16. Write chemical equations to show what happens when :
(i) Sulphur powder is heated with cone H2SO4. (if) Cinnabar is roasted in a furnace (iii) Sulphur dioxide is dissolved in water. 3


17. The heat produced by burning of cowdung cake of mass 210 g raised the temperature of 50 g of water by 2°C, Assuming that all the heat was utilised for heating water whose specific heat capacity is 4.2 J/g°C, Calculate the calorific value of Aid.

OR

Heat produced on buring 5.0 g of fuel raises the temperature of 1.0 Kg of water from 20° to 60° C. If the specific heat of water is 4.2 J/g °C, calculate calorific value of fuel. 3


18. Explain the principle of working of a (i) Electric Motor and (it) A.C. Generator. 5 Write the basic rules used to explain their working.


19. Explain the following terms giving an example :
(i) Addition reaction (ii) Tollen’s reagent test
(iii) Saponification (V) Decarboxylation
(v) Polymerisation.
OR
Explain fractional distillation of petroleum with the help of neat and labelled diagram. Name four fractions and give the uses of each fraction. 5


20. State Ohm’s law. When two resistors R1 and R2 connected in parallel to a source of energy, find the equivalent resistance. In the circuit given below if R1, R2 and R3 have 15 Ωt 30 Ω and 45 Ω respectively and the battery has 15 volt.
Calculate
(i) the equivalent resistance.
(ii) current drawn from battery,
(iii) the current through each resistor, (1+2+1 + 1)

Section - B

21. What do you mean by evolution ?


22. Which part of roots is involved in exchange of respiratory gases ?


23. What do you understand by biological magnification ?


24. What is the excretory waste in Amoeba and Earthworm ?


OR

What is the role of skin in excretion ?


25. Differentiate between axon and dendron.


26. What are the disadvantages of vegetative propagation ?


27. Why did Mendel select garden pea for his experiments ?


28. Differentiate between biodegradable and non-biodegradable pollutants.


29. What arc the functions of plant hormones ?


30. Describe the internal structure of the human heart. Where is pacemaker located and what is its function?


OR

Explain the various steps of coagulation of blood. 5