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PHYSICS [2 Mark Question Answer]

Heat and Energy · ICSE STD 9 (ICSE - English Medium). 24 questions.

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[2 Mark Question Answer]

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24 questions · timed · auto-graded

Question 12 Marks
What causes the rise in atmospheric temperature?
Answer
With activities industrialization, deforestation, excess burning of fossil fuel, the concentration of green house gases has increased on earth's atmosphere. This increase in the amount of greenhouse gases present in atmosphere has caused the rise in atmospheric temperature.
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Question 22 Marks
What do you mean by greenhouse effect?
Answer
Greenhouse effect is the process of warming of planet's surface and its lower atmosphere by absorbtion of infrared radiations of longer wavelength emitted out from the surface of planet.
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Question 32 Marks
What is carbon tax? Who will pay it?
Answer
The tax calculated on the basis of carbon emission from industry, number of employee hour and turnover of the factory is called carbon tax.
This tax shall be paid by industries. This will encourage the industries to use the energy efficient techniques.
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Question 42 Marks
State two ways to minimize the impact of global warming.
Answer
  1. Use of renewable sources of energy to generate electricity in place of generating electricity from the fossil fuels based power plants.
  2. Controlling population through family planning, welfare reforms and the empowerment of women.
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Question 52 Marks
How will global warming affect the sea level?
Answer
Due to melting of polar ice and glaciers, there will be rise in sea level on coastal wet lands. It would raise worldwise sea level, thereby, many big cities in the coastal areas will be covered by sea water.
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Question 62 Marks
What will be the effect of global warming at the poles?
Answer
At the poles, due to increase in temperature, the snow and ice will melt which will cause flood in coastal countries. The icebergs of dark land and oceans will melt, so the dark land and oceans will become uncovered and will absorb more heat radiations coming from sun, increasing the green house effect further.
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Question 72 Marks
State the cause of increase of green house effect.
Answer
The increase in green house gases due to activities like industrialization, deforestation, natural gas exploration, burning of biomass, natural gas exploration, more use of gadgets like refrigerators has caused the increase of green house effect.
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Question 82 Marks
What is tidal energy ? Explain in brief.
Answer
Tidal energy: The energy possessed by rising and falling water in tides is known as tidal energy. Dams are constructed across a narrow opening to the sea to harness tidal energy and produce electricity. However, it is not a major source of energy as the rise and fall of seawater during tides is not enough to generate electricity on a large scale.
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Question 92 Marks
Why is the use of wood as a fuel not advisable although wood is a renewable source of energy?
Answer
Wood is obtained from trees. Hence, trees need to be cut down for wood to be used as a fuel.
Also, burning wood releases a lot of smoke which pollutes the atmosphere.
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Question 102 Marks
Select the renewable and non-renewable sources of energy from the following :
  1. Coal
  2. Wood
  3. Water
  4. Diesel
  5. Wind
  6. Oil
Answer
Renewable : Wood, Water and Wind
Non-renewable : Coal, Diesel and Oil
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Question 112 Marks
Name the two groups in which various sources of energy are classified. State on what basis are they classified.
Answer
The two groups in which various sources of energy are classified are renewable or non-conventional sources of energy and non-renewable or conventional sources of energy.
These sources are classified on the basis of their availability and utility.
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Question 122 Marks
What do you mean by degradation of energy? Explain it by taking two examples of your daily life.
Answer
The gradual decrease of useful energy due to friction etc. is called the degradation of energy.

Examples:

  1. When we cook food over fire, the major part of heat energy from the fuel is radiated out in the atmosphere. This radiated energy is of no use to us.
  2. When electrical appliances are run by electricity, the major part of electrical energy is wasted in the form of heat energy.
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Question 132 Marks
State four ways for the judicious use of energy.
Answer
Four ways for the judicious use of energy are:
  1. The fossil fuels such as coal, petroleum, natural gas should be used only for the limited purposes when there is no other alternative source of energy available.
  2. The wastage of energy should be avoided.
  3. Efforts must be made to make use of energy for community or group purposes.
  4. The cutting of trees must be banned and more and more new trees must be roped to grow.
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Question 142 Marks
What percentage of total electrical power generated in India is obtained from nuclear power plants? Name two places in India where electricity is generated from nuclear power plants.
Answer
At present only about 3% of the total electrical power generated in India is obtained from the nuclear power plants.
Tarapur in Maharahtra and Narora in Uttar Pradesh are the places where electricity is produced using nuclear energy.
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Question 152 Marks
State two advantages and two limitations of using wind energy for generating electricity.
Answer
Advantages of using wind energy:
  1. It does not cause any kind of pollution.
  2. It is an everlasting source.

Limitations of using wind energy:

  1. The establishment of a wind farm is expensive.
  2. A large area of land is needed for the establishment of a wind farm.
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Question 162 Marks
What is wind energy? How is wind energy used to produce electricity? How much electric power is generated in India using the wind energy?
Answer
The kinetic energy of the moving large masses of air is called the wind energy. Wind energy is used in a wind generator to produce electricity by making use of wind mill to drive a wind generator.
At present in India, more than 1025 MW electric power is generated using wind energy.
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Question 172 Marks
Differentiate between the producers and consumers.
Answer
Producers like plants and some bacteria are capable of producing its own food using the energy of sun but consumers are not capable of producing their own food. They depend on producers for food.
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Question 182 Marks
State the importance of green plants in an ecosystem.
Answer
Green plants absorb most of the energy falling on them and by the process of photosynthesis they produce food for the consumers. Plants, being primary producers are of great importance in the ecosystem. They also maintain the balance of oxygen and carbon dioxide on earth.
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Question 192 Marks
Distinguish between heat and temperature.
Answer
Heat is a form of energy obtained due to the random motion of molecules in a substance but temperature is a quantity which decided the direction of flow of heat when two bodies at different temperature are placed in contact. Two quantities having the same amount of heat may differ in temperature.
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Question 202 Marks
Explain the following
A glass bottle completely filled with water and tightly closed at room temperature is likely to burst when kept in the freezer of a refrigerator.
Answer
Inside the freezer, when the temperature of water falls below 4°C, the water in the bottle starts expanding. If the bottle is completely filled and tightly closed, there is no space for water to expand, and hence, the bottle may burst.
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Question 212 Marks
Explain the following
A hollow glass sphere which floats with its entire volume submerged in water at 4°C, sinks when water is heated above 4°C
Answer
On heating water above 4°C, the density of water decreases. As a result, the upthrust acting due to water on hollow glass sphere also decreases, which causes it to sink.
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Question 222 Marks
Explain the following
Fishes survive in ponds even when the atmospheric temperature is well below 0°C
Answer
The anomalous expansion of water helps preserve aquatic life during very cold weather. When temperature falls, the top layer of water in a pond contracts becomes denser and sinks to the bottom. A circulation is thus set up until water in the pond reaches its maximum density at 4°C. If the temperature falls further, then the top layer expands and remains on the top till it freezes. Thus, even though the upper layer are frozen, the water near the bottom is at 4°C and the fishes can survive in it easily.
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Question 232 Marks
Explain the following
In winter, water tanks (or ocean) start freezing from the surface and not from the bottom.
Answer
In winters, when temperature falls, the surface of water in the tank contracts, becomes denser and sinks to the bottom. A circulation is thus set up until the entire water in the tank reaches its maximum density at 4°C. If the temperature falls further, then the top layer expands and remains on the top till it freezes. Thus, water in a tank starts freezing from the top and not from the bottom.
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Question 242 Marks
Explain the following
Water pipes in colder countries often burst in winter.
Answer
On winter nights, as the atmospheric pressure starts falling below 4°C, water in the pipe lines expand and exert a great pressure on the pipes, causing them to burst.
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[2 Mark Question Answer] - PHYSICS STD 9 Questions - Vidyadip