Science class 8 important question

                                       PHYSICS

1. a. What is derived unit? Write any two importance of measurement in our daily life.  (1+2)

    b. What is acceleration? A motorbike travels 2.4 km. in 5 minute, calculate its average velocity. (1+1)

2. a. What is simple machine? The efficiency of a machine is always less than 100%, why?(1+1.5)

   b. What type of object floats on water? Write three factors affecting liquid pressure. Write a formula for liquid pressure.    (1+1+0.5)

3. a. What is transformation of energy? Calculate the power of a man, if he lifts a load of 17 N to a height of 25 m in 100 seconds.  (1+2)

    b. The temperature of boiling water cannot be measured by alcohol thermometer, why? What is the boiling point of mercury?  (2)

4. a. Define one joule work. Write the two types of work.  (1+1)

   b. define echo. Write the two conditions for the formation of echo. (1+2)

5. a. Write the two defects of a simple machine. Write the full form of MCB. Write a role of MnO₂ in a dry cell. (1+1+1)

    b. Define wavelength. How is sound produced? (1+1)                

                               CHEMISTRY

6. a. What is octet rule? Atom does not contain electric charge, why? Define molecular charge. (1+1+1)

     b. What is word equation? Write one use of sodium chloride. (1+1)

7. a. Write the molecular formula of i) sodium hydroxide ii) calcium carbonate (2)

    b. Which metal is extracted from hematite ore? Write one use of this metal. Define coinage metal. (1+1+1)

8. a. What is acid? Write the two properties of base. (1+2)

   b. What are represented by 1, 7, 14 in pH scale? Why is aluminum used to make an aero-plane? (1+1)

                                 BIOLOGY   

9. a. Define pollination. Draw a well labeled diagram of virus. (1+2)

   b. Write the two differences between monocotyledonous and dicotyledonous seeds.  (2)

10. a. Define sexual reproduction. What types of reproduction are found in the following animals i) hydra  ii) amoeba  iii)frog  iv) cow. (1+2)

   b. Write a function of WBC. The walls of artery are thicker, why? (1+1)

11. a. Which blood cell contains hemoglobin? What is its function? (1+1)

    b. Give two reasons for the modification of stem of a plant in different forms. Define photosynthesis.  (2+1)

                          ASTRO+GEO

12. a. Write any three methods for the conservation of soil.   (3)

    b. What are the two bases for the existence of life on the earth?  (2)

                                       ENVIRONMENT

13. a. Write the two causes of deforestation. Suggest any one way to stop it. (2+1)

     b. Write any two negative effects of air pollution.  (2)

14. a. Name any two gases that increases the temperature of the earth. Write the two importance of planting trees   (1+2)

     b. Write any two importance of medicinal plants. (2)

15. a. Write any three safety measures that should be adopted after an earthquake. (3)

     b. Define water pollution. Write one cause of water pollution.   (1+1)

                                           THE END