400. Halley"s comet appears in the heavens once in
   (a) 40 years
   (b) 50 years
   (c) 76 years
   (d) 80 years
Ans: (c)
401. The planet that is known as earth"s twin is
   (a) Mercury
   (b) Venus
   (c) Moon
   (d) Mars
Ans: (b)
402. The temperature, surface features, length of days and nights of a planet
   depend on
   (a) its atmosphere
   (b) its distance from the sun
   (c) its rotation
   (d) All the above
Ans: (d)
403. The earth"s nearest neighbour in space is
   (a) the Sun
   (b) the Moon
   (c) the Venus
   (d) the Mars
Ans: (b)
404. The asteroids belt lies between the orbits of
   (a) Earth and Mars
   (b) Venus and Earth
   (c) Mars and Jupiter
   (d) Moon and Mars
Ans: (c)
405. The difference between planets and stars is