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An artificial satellite orbiting around the Earth does not fall down. This is so because the attraction of Earth
(a)
does not exist at such a distance.
(b)
is neutralized by the attraction of the moon.
(c)
provides the necessary speed for its steady motion.
(d)
provides the necessary acceleration for its motion.
(D)
The surface of a lake is frozen in severe winter, but the water at its bottom is still liquid. What is the reason?
Ice is a bad conductor of heat.
Since the surface of the lake is at the same temperature as the air, no heat is lost.
The density of water is maximum at 4°c.
None of the statements (a), (b) and (c) given is correct.
(C)