46 .In nuclear raeactors the speed of neutrons is slowed down by -
A.  heavy water
B.  ordinary water
C.  zinc rods
D.  moten caustic soda
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47 .The phenomenon of radioactivity was discovered in 1898 A. D. by-
A.  Henri Becquerel
B.  J.J Thomson
C.  `Marie Curie
D.  Pierre Curie
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48 .Heavy metal got their name because compared to other atoms they have
A.  Higher atomic number
B.  Higher atomic radii
C.  Higher atomic masses
D.  Higher densities
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49 .Chemical name of vitamin A is -
A.  Thiamine
B.  axerophthol (acid)
C.  Ascorbic acid
D.  nicotinamide
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50 .Gas used for artificial ripening of fruits is:
A.  Ethane
B.  Acetylene
C.  Propane
D.  Methane
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51 .The process by which vegetable ghee is manufactured is known as-
A.  Saponification
B.  Hydrogenation
C.  Esterification
D.  Dydrolysis
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52 .The α - particles are-
A.  High energy electrons
B.  Positively charged hydrogen ions
C.  High energy x –ray radiations
D.  double positively charged helium nuclei
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53 .Chemically vermillion is
A.  Calcium Carbonate
B.  Potassium Nitrate
C.  Potassium Sulphide
D.  Merucry (II) Sulphide
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54 .Which of the following is responsible for permanent hardness of water?
A.  Magnesium bicarbonate
B.  Sodium chloride
C.  Calcium sulphate
D.  Calcium bicarbonate
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55 .Cid rain is due to
A.  Sulphur dioxide pollution
B.  Carbon monoxide pollution
C.  Pesticide pollution
D.  Dust particules in the atmosphere
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56 .Which is fight and flight organ?
A.  Adrenal
B.  Thyroid
C.  Pituitary
D.  Kidney
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57 .Rate of diffusion of a gas is -
A.  Directly proportional to its density
B.  Directly proportional to its molecular mass
C.  Directly proportional to the square of its molecular mass
D.  Inversely propostional to the square root of its molecular mass
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58 .If a refrigerator's door is kept open, then-
A.  Room will be cooled
B.  Room will be heated
C.  May get cooled or heated depending upon the weather
D.  No effect on room
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59 .The gas used to extinguish fire is -
A.  Neon
B.  Nitrogen
C.  Carbon dioxide
D.  Carbon monoxide
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60 .The ultraviolet rays can be checked by -
A.  Flint glass
B.  Crooke's glass
C.  Soda glass
D.  Pyrex glass
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