If you are searching DAV Class 8 Science Half Yearly Question Paper, then you will at a right place. Here you will get all subject solution of DAV, NCERT.
Class - VIII
SCIENCE & TECHNOLOGY
(TERM - 1)
Time Allowed : 3 Hrs
Maximum Marks : 80
General Instructions :
1. All questions are compulsory.
2. There is no overall choice. However internal choice have been provided in 3 questions of 3 marks category and 3 questions of 5 marks category.
3. Ques. 1 to Ques. 8 are very short answer type and carry 1 mark each.
4. Ques. 9 to Ques. 17 are short answer type II and carry 2 marks each.
5. Ques. 18 to Ques. 25 are short answer type I and carry 3 marks each.
6. Ques. 26 to Ques. 31 are long answer type questions and carry 5 marks each.
1. Sonakshi went to a village for the first time. She saw a farmer was sun drying grains before storing them. What could be the reason? 1
2. In states like Rajasthan, the farmers use drip irrigation system in spite of sprinkler system. Why? 1
3. Carbon monoxide when inhaled, passes through the lungs into the blood. It combines with the hemoglobin of blood to form which complex substance . 1
4. Two glasss jars A and B are filled with carbon dioxide and oxygen gases, respectively. In each jar a lighted candle is placed simultaneously. In which jar will candle remain lighted for a long time and why? 1
5. In which zone of a candle flame do the wax vapours burn completely. 1
6. Name the bacteria that convert milk into curd. 1
7. When electricity is passed through distilled water the bulb does not glow. Suggest a method that can make the bulb glow. 1
8. A girl is pushing a box towards east direction. In which direction should her friend push the box so that it moves faster in same direction. 1
9. Define Friction. 2
10. Vandana and Reena went to a zoo and got to know there, that some species are unique to particular geographic location, such as a specified island, some habitat type, a nation or some other well defined zone. She wanted to know following about them : 2
a) What is the name given to such species?
b) Give one example of the above species and it's location.
11. Earthquake is a student tremor or movement of earth's crust, which usually lasts only for a very short time. 2
a) Name the scale used to measure the intensity of the earthquake.
b) City A experience an earthquake of magnitude 4.5 . What would be the effect of earthquake.
12. In many situations, friction is undesirable and we would want to minimize it. Write two ways that can reduce friction. 2
13. The biggest threat to the existence and survival of wild animals and birds is deforestation. Write two consequences of deforestation. 2
14. Write two harmful effects of acid rain. 2
15. Choose the odd one out from the following and give reason for your choice : 2
a) Firewood, Charcoal, Coal, Petrol
b) Natural gas, Sun , Biomass, Wind
16. Whenever an object moves , or tends to move over the surface of another object, there is force of friction. List two factors on which this force of friction depends. 2
17. Give reason for the following : 2
a) Paddy and maize are grown during the months from June to October ( Kharif Crop)
b) Seedlings of paddy are planted in standing water at appropriate distance.
18. In many modern cities, air pollution is a serious problem. Suggest three ways to reduce the level of air pollution in such cities. 3
19. The earthquake strike suddenly and violently, without warning, at any time of the day Or night. If sn earthquake occurs in a populated area, it can cause injuries, death and property loss. Write three necessary precautions that should be taken before hand to protect ourselves from the potential hazards. 3
20. Friction is needed for so many activities in our daily life. Write any three situations where friction is desirable. 3
Or
In some machines like hovercraft, it may not be advisable to use oil as a lubricant.
a) Which lubricant is used in hovercrafts?
b) Write two advantages of using it as a lubricant.
21. It is dark coloured, visicous and foul smelling liquid, often called liquid gold. 3
a) Identify this fossil fuel.
b) Give one of it's product and it's use.
Or
Economic devlopment, burning if fossil fuels and rapidly growing population are putting a strain on the environment, infrastucture and different natural resources.
a) Name two cleaner fuels which we should use to control the problem.
b) Write two advantages of using these fuels.
22. Indian subcontinent plays a host to a number of migratiry birds in summers as well as winters. It is estimated that over hundred species of migratory birds fly to India. Give the following information about them : 3
a) What is Migration?
b) Write two reasons of migration.
Or
Government of India is setting up biosphere Reserves, national parks and wildlife sancturies in different parts of the country to conserve biodiversity Fill in the missing gaps about them :
Location Protected animal
a) Bandipur __________ _________________
National Park
b) Jayakwadi ___________ Bird
Sanctuary
c) Gargimatha
Sanctuary _______________ ____________
d) Kaziranga
National Park Assam ___________
23. The calorific values of petrol and CNG are 45000 kJ/ kg and 50000 kJ / Kg, respectively. Ram has a vehicle which can run on a petrol as well as CNG. 3
a) Which fuel should be used by Ram?
b) Write two benefits of using that fuel.
24. The chemical effects of current ( electrolysis) have some important scientific and industrial applications. Enlist three of these applications. 3
25. Since ancient times microorganisms 'X' has been used for the large scale production of alcohol or wine. The conversion of sugar to alcohol is known as 'Y'. Gas 'Z' is produced during this process. What are X, Y and Z.
26. List mode of transmission and two preventive measures each for the following : 5
a) Cholera
b) Malaria
Or
Food preservation is the process of treating and handling food so as to stop, or greatly slow down , spoilage caused, or accelarated by microorganisms. Breifly describe about fine methods of food preservation.
27. Akanksha has made two paper cups by folding a sheet of paper. She half fills one of the cups with water and keeps the other empty. She puts those two paper cups above the flame carefully. 5
With reference to the above activity answer the following questions :
a) Which zone of the flame is best for heating?
b) What happens to the empty paper cup when it is heated?
c) What happens to the paper cup with water and why?
d) What will be the change in temperature of water?
Or
Fuel like Coal, LPG, CNG and Petrol etc. Produce heat energy on burning in air. Increased fuel consumption has led to harmful effects on environment.
a) Briefly describe two harmful effects of increased fuel consumption.
b( Write three characteristics of a good fuel.
28. Crops take nutrients from the soil for their proper growth. If farmers continue to grow the same crop year after year in the same field, the yield gradually decreases. 5
a) Why the yield gradually decreases on growing same crop tear after year.
b) Write about four methods to replenish the fertility of the soil.
29. Coal is a fossil fuel which is readily combustible black Rock or brownish black sedimentary rock. Coal is extracted from the ground by coal mining. 5
a) How was coal formed?
b) Write two uses of coal.
c) Write one advantages of using coal as a fuel.
30. In 1831 , Michael Faraday an English scientist, discovered a very important phenomenon, which is used to generate electric current by changing a magnetic field. 5
a) Name the phenomenon discovered by Michael Faraday that is used to generate electricity .
b) List any three experimental observations of Faraday and Henry.
c) In which devices the phenomenon of electromagnetic induction forms the underlying principle?
Or
Electroplating is a very useful process widely used in industries.
a) What is electroplating ?
b) List two conditions that help in getting a smooth and fine deposit during electroplating.
c) Write it's two practical applications.
31. a) Express pressure in terms of thrust. 5
b) The decrease in the pressure of a given force , through an increase in the surface area over which the force acts, finds many applications in our day to day life. List two such applications.
c) Climbers who attempt to scale high range mountains need to carry oxygen cylinders with them. Why?
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