16 .Heavy water is used as moderator a nuclear reactor. The function of the moderator is
A.  to control the energy released in the reactor
B.  to absorb neutrons and stop the chain reaction
C.  to cool the reactor
D.  to slow down the neutrons to thermal energy
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17 .A large iceberg melts at the base but not at the top becaue
A.  The base of iceberg remains in warmer conditions
B.  ice at the base contains impurities
C.  higher pressure at the base lowers the melting point of ice.
D.  ice at the top is different kind
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18 .Red data book gives information about species which are-
A.  Extinct
B.  Endagnered
C.  Dangerous
D.  Rare
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19 .If temperature rises, the coefficient of viscosity of liqid:
A.  decreases
B.  incrases
C.  remains unchanged
D.  none of these
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20 .Blue colour of the sky is consequence of
A.  reflection
B.  refraction
C.  scattering
D.  dispersion
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21 .The temperature of boiling water in a steam engine may be high because:
A.  there are dissolved substances in water
B.  there is low pressure inside the boiler
C.  there is high pressure inside the boiler
D.  the fire is at very high temperature
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22 .Electricity is produced through dry cell from
A.  Chemical energy
B.  Thermal energy
C.  Mechanical energy
D.  Nuclear energy
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23 .The head mirror used by E.N.T. doctors is
A.  Cancave
B.  convesx
C.  plane
D.  planoconvex
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24 .With rise of boiling point of water the latent heat of steam:
A.  Decreases
B.  Increased
C.  Does not change
D.  None of these
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25 .A change of 10° C in Centigrade scalecorresponds to what change in Fahrenheitscale
A.  18° F
B.  21°F
C.  10°F
D.  15°F
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26 .Metals are good conductor of heat than insulator because
A.  their atoms are relatively aprt
B.  they contain free electron
C.  they have reflecting surface
D.  none of these
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27 .Which of the following factors can decrease biological oxygen demand (BOD) of any freshwater ecosystem?
A.  Large amount of sewage
B.  Lrage biomass accumulation and decomposition
C.  Increased organic matter pollution
D.  Low temperature and low plant biomass accumulation
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28 .Which of the following is biodegradable?
A.  Paper
B.  D.D.T.
C.  Aluminium
D.  Plastic
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29 .Chlorofluro carbons are widely used in:
A.  Micro overns
B.  Solar heaters
C.  Washing machines
D.  Refrigerators
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30 .A small and a large rain drops are falling through air:
A.  the large drop moves faster
B.  The small drop moves faster
C.  Both moves with same speed
D.  None of the above
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