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NCERT 7th Class (CBSE) Science: Chemical and Chemical Changes

8th Science Periodic Test II (2018-19)

8th Science Periodic Test II (2018-19)

School Name: Venkateshwar Global School, Sector 13, Rohini, Delhi 110085 India
Time: 3 hour
M.M. 80 marks
Date: 24/09/2018
Class: VIII

General Instructions:

  1. All Questions are compulsory.
  2. Read the paper carefully and write all your answers only on the Answer Sheets provided separately.
  3. 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?

distance between

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:

  1. Aluminium foil is used to wrap food items
  2. Silver articles corrode easily now a days.
  3. There is a difference in sound upon dropping a metal coin and piece of coal.

Question: 11. Explain why:

  1. Schoolbags have broader straps.
  2. 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.

  1. Resultant force while going downstream (the direction of the river add boat is the same)
  2. 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.

Question: 21.

  1. Why is nitrogen gas filled in chips packets?
  2. Who is closer to plants  an algae or a protozoan? Why?
  3. 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:

  1. Aluminium is added to copper sulphate solution.
  2. Iron reacts with oxygen and moist air.
  3. Copper reacts with magnesium sulphtae.
  4. Potassium reacts with water.
  5. Iron reacts with steam.

Question: 24.

  1. Discuss three situations where friction is disadvantageous.
  2. Give two methods by which friction between two surfaces in contact can be reduced.

Question: 25. Draw a ray diagram to represent the image formed by a convex lens when the object is kept at a distance twice its focal length. Mention the characteristics of the image formed.

Question: 26. Describe the common properties of plastic. State the applications of each property.

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