8th Science Periodic Test II (2018-19)
Time: 3 hour
M.M. 80 marks
- All Questions are compulsory.
- Read the paper carefully and write all your answers only on the Answer Sheets provided separately.
- Draw the diagrams neatly only with a pencil.
Very short answer questions: (1×3 = 3 marks)
Question: 1. What do you mean by reactivity series of metals?
Question: 2. Name the part of the eye which gives colour to the eye.
Question: 3. Which device is used to measure atmospheric pressure?
Short answer questions (I) (2×6 = 12 marks)
Question: 4. Why does a mango get spoilt after few days but mango pickle does not spoil for a long period of time?
Question: 5. Explain the term monomer and polymer with the help of examples.
Question: 6. Iqbal has to pus a light box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
Question: 7. Calculate the number of images formed by plane mirrors at an angle of 10° to each other.
Question: 8. The distance between the object and its image formed by a plane mirror appears to be 24 cm. What is the distance between the mirror and the object?
Question: 9. While standing before a plane mirror, if you move your right hand, Which hand does your image move? Why?
Short answer question (II): (3×10 = 30 marks)
Question: 10. Give reasons:
- Aluminium foil is used to wrap food items
- Silver articles corrode easily now a days.
- There is a difference in sound upon dropping a metal coin and piece of coal.
Question: 11. Explain why:
- Schoolbags have broader straps.
- Deep sea divers wear special suits.
Question: 12. Name the three types of musical instruments. How is sound produced in each type?
Question: 13. Zinc sulphate forms a colorless solution in water. Will you observe any colour change on adding copper to it? Explain why.
Question: 14. Distinguish between myopia and hypermetropia. (any three points)
Question: 15. How is sound produced in our throat?
Question: 16. List three steps you can take to reduce the danger that plastics pose to the environment.
Question: 17. An elephant which weighs 20,000 N stands on one foot of area 1000 cm2. How much pressure would it exert on the ground?
Question: 18. How does a vaccine work? Who indented the first vaccine?
Question: 19. Ritu rows at boat with a force of 700 N while running water applies a force of 500 N. Calculate the following.
- Resultant force while going downstream (the direction of the river add boat is the same)
- Resultant force while going upstream (the direction of the river is opposite to the direction in which the boat is moving).
Long answer questions: (5×7 = 35 marks)
Question: 20. With the help of an activity and a diagram, show how the pressure exerted by liquids increases with depth.
- Why is nitrogen gas filled in chips packets?
- Who is closer to plants an algae or a protozoan? Why?
- We should complete the course of antibiotics prescribed by the physician. What would happen if we leave the course midway?
Question: 22. Define noise. Mention any two sources of noise pollution. List three methods of controlling noise pollution.
Question: 23. Explain with the help of a chemical reaction what happens when:
- Aluminium is added to copper sulphate solution.
- Iron reacts with oxygen and moist air.
- Copper reacts with magnesium sulphtae.
- Potassium reacts with water.
- Iron reacts with steam.
- Discuss three situations where friction is disadvantageous.
- Give two methods by which friction between two surfaces in contact can be reduced.