51) Planets are always small compared with stars because otherwise ______.
( a) the rotation of the planets would cause them to disintegrate
(b) the great mass of the planets would cause them to be pulled into their parent star
(c) the great mass of the planets would prevent them from being held in orbit and they would escape
(d) the planets would be stars themselves
Answer: (d)
52) The least likely reason why planetary systems have not been directly observed around stars other than the sun is that __
(a) Planets are small
(b) Planets shine by reflected light
(c) Planetary systems are rare
(d) Other stars are far away
Answer: (c)
53) Which of the following is the correct ordering of the inner planets according to their proximity to the sun? (CSS 2012)
(a) Jupiter, Saturn , Uranus , Neptune
(b) Phobos, Deimes , Europe , Tias
(c) Mercury, Venus, Earth, Mars
(d) None of these
Answer: (c)
