» CBSE Science Practice Paper : Set VIII : CBSE Sample Question Papers

Section - A

1. Name any two non-renewable sources of energy. 1
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2. Write any two examples of harmful radiations emitted by the nuclear wastes ? 1
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3. What will happen to white light on entering a prism ? 1
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4. Wright Me equation for laboratory preparation of hydrogen gas. 1
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5. Win-it a wire of resistance R, length / is made into a circle, what is the resistance between two points at the end of its diameter ?

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Why do we use semiconductors more in electronic devices. 1
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6. How can we use solar energy to overcome energy crisis ? 2
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7. Calculate pH of the solution when hydrogen ion concentration is 1.0 x 10^{-6 M. 2
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8. What is a wind mill ? Give two advantages and disadvantages of wind mill. 2
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9. What is meant by annealing of glass ? What type of glass do we get by this process ? 2
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10. If three 60 W bulbs are used for 6 hours a day and a tube light of 40 W is used for 4 hours, calculate the cost of electricity in a month of 30 days, if the cost of 1 unit is Rs. 2.50. 2
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11. Write two examples of ‘fossil fuel’. Why are they preferred over wood ? 3
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12. Draw a labelled diagram of Alternating current generator, 3
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13. What is total internal reflection ? Relate the angle of incidence and the refractive index for total internal reflection. Write the conditions necessary for total internal reflection. 3
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14. What are constituents of bronze ? Write its two main uses. Name the common constituent of brass, bronze and german silver.

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What type of mixtures are separated by fractional distillation ? Name the fraction of crude oil whose boiling point is more than 350⁰C. Where is it mostly used as a fuel ? 3
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15. What is the meaning of power of a lens ? When a convex lens of focal length 10 cm and concave lens of focal length 20 cm are placed in contact, find the equivalent focal length and power.

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A convex lens of 10 cm focal length and a concave lens of 20 cm focal length are kept in contact, how does the combination behave. Give reason. 3
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