(b) Apogee
    (c) Aphelion
    (d) Perihelion
Ans: (c)
81. When the earth is at its minimum distance from the Sun, it is said to be _____.
    (a) Perigee
    (b) Apogee
    (c) Aphelion
    (d) Perihelion
Ans: (d)
82. What is the primary cause of the day and night?
    (a) Rotation
    (b) Revolution
    (c) Earthquake
    (d) Sun strom
Ans: (a)
83. What is the primary cause of seasonal change on the surface of the earth?
    (a) Earth"s revolution and inclination of its axis
    (b) Earth"s rotation and inclination of its axis
    (c) Revolution
    (d) Rotation
Ans: (a)
84. What is siderial day?
    (a) Time taken by the earth to complete one revolution with respect to the Moon
    (b) Time taken by the earth to complete one rotation with respect to a fixed star at infinity
    (c) Time taken by the earth to complete one rotation with respect to the Moon
    (d) Time taken by the earth to complete one rotation with respect to the Sun
Ans: (b)
85. What is a "synodic month"?
    (a) Moon"s period of rotation on its axis with respect to the earth.
    (b) Moon"s period of revolution with respect to the Sun
    (c) Moon"s period of revolution around the earth.
    (d) Moon"s period of revolution with respect to a star at infinity
Ans: (b)
86. On which date is the Earth in "perihelion"?
    (a) June-21
    (b) August-15
    (c) January-3
    (d) December-21
Ans: (c)
87. On which date is the Earth in "aphelion"?
    (a) September-23
    (b) December-22
    (c) July-4
    (d) June-21
Ans: (c)
88. The taken by the Moon in completing one revolution around the Earth is _____.
    (a) 27.5 days
    (b) 29.5 days
            1
    (c) 27 days
            3
            1
    (d) 29 days
            3
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