Questions

[1 Mark Question Answer]

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27 questions · timed · auto-graded

Question 11 Mark
What do you mean by global warming?
Answer
Global warming means the increase in average effective temperature near the earth's surface due to an increase in the amount of green house gases in its atmosphere.
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Question 21 Mark
State the effect of green house gases on the temperature of earth's atmosphere.
Answer
The greenhouses gases have an average warming effect on Earth's surface of about $15.5^\circ C ($or $60^\circ F).$
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Question 31 Mark
What would have been the temperature of earth's atmosphere in absence of green house gases in it?
Answer
In absence of green house gases, the average temperature on earth would be $-18.$
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Question 41 Mark
Name the radiations which are absorbed by the green house gases.
Answer
Infrared radiations of long wavelength are absorbed by the green house gases.
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Question 51 Mark
What results in the increase of carbon dioxide contents of earth's atmosphere?
Answer
The concentration of carbon-di-oxide content's of earth's atmosphere has increased due to industrial growth, combustion of fossil fuels and clearing of forests.
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Question 61 Mark
Which of the following solar radiations pass through the atmosphere of Earth: $X -$rays, ultraviolet rays, visible light rays or infrared radiation?
Answer
Visible light rays and short infrared radiation pass through the atmosphere of earth.
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Question 81 Mark
How will global warming affect the agriculture?
Answer
Global warming will cause drastic changes in the patterns of wind, rainfall etc. Thus it will result in low agricultural yield.
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Question 91 Mark
State the effect of global warming in coastal regions.
Answer
Due to global warming, the snow and ice around the poles will melt and cause flood in coastal countries.
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Question 101 Mark
The conversion of part of energy into a unuseful form of energy is called $...........$
Answer
The conversion of part of energy into a unuseful form of energy is called degradation of energy.
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Question 111 Mark
State two characteristics which a source of energy must have.
Answer
  1. A source of energy should be safe and convenient to use.
  2. A source of energy should be economical and easy to store and transport.
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Question 121 Mark
State the energy transformation in the following:
electricity is obtained from nuclear energy.
Answer
Nuclear energy $($or heat energy$)$ into electrical energy.
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Question 131 Mark
State the energy transformation in the following:
electricity is obtained from hydro energy.
Answer
Mechanical energy into electrical energy.
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Question 141 Mark
State the energy transformation in the following:
electricity is obtained from wind energy.
Answer
Mechanical energy into electrical energy.
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Question 151 Mark
State the energy transformation in the following:
electricity is obtained from solar energy.
Answer
Light energy into electrical energy
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Question 161 Mark
What is the source of energy for all ecosystems?
Answer
The source of energy for all ecosystems is the Sun.
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Question 171 Mark
Name two substances which contract on heating.
Answer
Water contracts on heating from $0^\circ C$ to $4^\circ C.$
Silver iodide contracts on heating from $80^\circ C$ to $141^\circ C.$
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Question 191 Mark
What do you understand by thermal expansion of a substance?
Answer
The expansion of a substance on heating is called the thermal expansion of the substance.
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Question 201 Mark
Why does a piece of ice when touched with a hand, appear cool? Explain.
Answer
On touching a piece of ice, heat flows from our hand $($hot body$)$ to the ice $($cold body$),$ and hence, it appears cold.
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Question 211 Mark
Define temperature and write its $S.I.$ unit.
Answer
Temperature is the parameter which tells the thermal state of a body $($i.e. the degree of hotness or coldness$).$
The $S.I.$ unit of temperature is 'kelvin'.
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Question 221 Mark
Name the $S.I.$ unit of heat and how is it related to the unit calorie?
Answer
$S.I.$ unit of heat is 'joule'.
$1$ joule $= 0.24$ cal
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Question 231 Mark
Two bodies at different temperatures are placed in contact. State the direction in which the heat will flow.
Answer
Heat will flow from a hot body (body at a higher temperature) to a cold body (body at a lower temperature).
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Question 241 Mark
What is heat ? Write its S.I. unit.
Answer
Heat is the energy of random motion of molecules constituting the body.
Its S.I. unit is 'joule'.
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Question 251 Mark
A deep pond of water has its top layer frozen during winter. State the expected temperature of water layer (i) Just in contact with ice and (ii) At the bottom of pond.
Answer
(i) Water just in contact with ice is at 0°C.
(ii) Water at the bottom of the pond is at 4°C.
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Question 261 Mark
At what temperature is the density of water is maximum? State its value.
Answer
Density of water is maximum at $4^{\circ} C$. Its value is $1000 kgm ^{-3}$.
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Question 271 Mark
What do you mean by the anomalous expansion of water?
Answer
The expansion of water when it is cooled from 4°C to 0°C is known as the anomalous expansion of water.
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