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Cracker on ignition produces sound. Why?
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The calorific values of petrol and CNG are 45000 kJ/kg and 50,000 kJ/kg respectively. If you have vehicle which can run on petrol as well as CNG, which fuel will you prefer and why?
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Forest fire produces a lot of air pollution. Write in brief about the reasons of forest fires.
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Why is it important to conserve forests?
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Mention any one action that you have undertaken to conserve trees.
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State whether the following statement is True or False. Correct the false statement.
Plants of a particular area are collectively termed as fauna.
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Name the first Reserve Forest of India.
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Mention the aim of Forest (Conservation) Act.
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In the circuit shown in the following figure, when the circuit is completed, the hammer strikes the gong. Which of the following force is responsible for the movement of hammer?
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If we apply oil on door hinges, the friction will
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You might have noticed that when used for a long time, slippers with rubber soles become slippery. Explain the reason.
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We have a stringed musical instrument. The string is plucked in the middle first with a force of greater magnitude and then with a force of smaller magnitude. In which case would the instrument produce a louder sound?
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Which of the following solutions will not make the bulb in figure?
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We can see a non-luminous object when the light
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Light is falling on surfaces S1 S2 and S3 as shown in the following figure.
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Surfaces on which the angle of incidence is equal to the angle of reflection is/are
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A small hole P is made in a piece of cardboard. The hole is illuminated by a torch as shown in the following figure. The pencil of light coming out of the hole falls on a mirror.
At which point should the eye be placed, so that the hole can be seen?
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Two mirrors A and B are placed at right angles to each other as shown in the following figure.
A ray of light incident on mirror A at an angle of 25° falls on mirror B after reflection. The angle of reflection for the ray reflected from mirror B would be
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How many times is a ray of light reflected by two plane mirrors placed parallel and facing each other?
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The angle between incident ray and reflected ray is 60°. What is the value of angle of incidence?
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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?
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