Mirage is due to

A) unequal heating of different parts of the atmosphere
B) magnetic disturbances in the atmosphere
C) depletion of ozone layer in the atmosphere
D) equal heating of different parts of the atmosphere

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Light year is a unit of

A) time
B) distance
C) light
D) intensity of light

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Metals are good conductors of electricity because

A) they contain free electrons
B) the atoms are lightly packed
C) they have high melting point
D) All of the above

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Planets do not twinkle because

A) they emit light of a constant intensity
B) their distance from the earth does not change with time
C) they are very far away from the earth resulting in decrease in intensity of light
D) they are nearer to earth and hence we receive a greater amount of light and, therefore minor variations in the intensity are not noticeable

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The absorption of ink by blotting paper involves

A) viscosity of ink
B) capillary action phenomenon
C) diffusion of ink through the blotting
D) siphon action

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