We cannot see the dark side of Mercury because ………….

47. C

Mercury always keeps one side towards the sun. On this side it is always day, on the other side always night. We only see the lighted side.

48. D.

The nearest planet to the sun, it is always seen near the sun, either just before sunrise or soon after sunset.

49: A

Mercury is half the size of the earth. Because it is much lighter, it has much less gravity.

50. B

47. C

48. D.

49: A

50. B

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