51)  “Parsec” represents the distance at which the mean radius of earth’s orbit subtends an angle of one second of an arc. It equal to               3.26 light years.

52) Sun’s period of revolution around the galactic centre is 250 million years and is called as “cosmic/Galactic year”.

53) The distance travelled by light in one year in vacuum is called light year.       

54) “Astronomical unit” is the  mean distance between the earth and the sun and is  estimated to be 1.49 x 108 km.

55) The diameter of mars is approximately 6794 Km.

56) The science dealing with nature and origin of universe is known as “Cosmology”.

57) Around July4th the earth is farthest from the sun (152 million km) and is known to be “Apehelion”.

58)       Earth is closest to sun on Jan3 (at a distance of about 197 million kms) and is said to be at “Perihelion”.

59)       Earth has three layers i) the crust ii) the mantle iii) the core

60)   The study of seismic waves is called “seismic tomography”.

61)   A great circle on the globe is one whose plane passes through the centre of globe (earth).

62)   Great circle represents circumference of the earth.

63)   Great circle is the greatest possible circle on globe.

64)   All the meridians and only the equator form great circle.

65)   First nuclear test in India was made in 1974, May 18th at Pokhran in Rajasthan.

66)   A dentist uses a concave lens to examine small cavities in the teeth.

67)   Diamond is the crystalline form Carbon.

68)   The source of solar energy is Nuclear fusion.

69)   The first metal used by man was copper.

70)   Velocity of wind is measured by “Anemometer”.

71)   When milk is churned, the cream from it is separated due to centrifugal force.

72)   Rectifiers are used to convert AC to DC.

73)  The colour of the ocean appears to be blue because of the sunlight falling on it is scattered.

74)   The element used in storage batteries is lead.

75)  Largest asteroid discovered so far is “Ceres”.

76)  A superior planet is the one whose orbit lies beyond that of earth.

77)   In nuclear fission, the energy is released as light.  

78)  “Choke” is used to reduce the current in AC circuit.

79)   Kilowatt-hour is a unit of energy.

80)  Concept of geostationary orbit was suggested by “Arthur C. Clarke”.

81)   The unit used to measure the supersonic speed is Mach.

82)   The wire used in the filament of house hold bulbs has high resistance and high melting point.

83)   Emission of beta particles will produce “Isobars”.

84)  Only one tenth of an iceberg is visible above the surface of sea.

85)  Microwaves are used for telecommunication via artificial satellites.

86)  Photostat machine works on electrostatic image making technology.

87)  Diode is used for rectification.

88)   Minimum escape velocity of a rocket to be launched into space is 11.2 km/sec.

89)   If a simple pendulum is taken to the moon, its frequency of vibration will decrease.

90)   Rain water would be most suitable for use in boilers.

91)   The pitch of sound depends on frequency alone.

92)  The ratio of RMS value to the peak value of an alternating current is 1/sqrt(2).

93)   The working principle of a washing machine is centrifugation.

94)   Hydrogen has the highest fuel value.

95)   In a car battery the electrolyte used is Hydrochloric acid.

96)   “Transformer” is the device used to step down or up the voltage of alternating current.

97)   In an electric cell the nucleus is not found.

98)   The tape of tape recorder is coated with ferromagnetic powder.

99)   Capillary action is a result of surface tension.

100) Melting point of ice is 0 oC.