Ans: (d)
144. The pressure exerted on the ground by a man is greatest [CDS 2010]
   (a) when he lies down on the ground
   (b) when he stands on the toes of one foot
   (c) when he stands with both feet flat on the ground
   (d) all of the above yield the same pressure
Ans: (b)
145. Which one of the following is not needed in a nuclear fission reactor?
   [CDS 2010]
   (a) Moderator
   (b) Coolant
   (c) Accelerator
   (d) Control device
Ans: (c)
146. The shortest unit of length is: [UPPCS (Pre) 2005]
   (a) micron
   (b) nanometer
   (c) angstrum
   (d) fermimeter
Ans: (b)
147. An endoscope, used by doctors for examine the inside of a patient"s
   stomach, works on the principle of : [JPSC (Pre) 2011]
   (a) reflection of light
   (b) dispersion of light
   (c) refraction of light
   (d) total internal reflection of light
Ans: (d)
148. If two conducting spheres are separately charged and then brought in
   contact: [NDA, 2010]
   (a) the total energy of the two spheres is conserved
   (b) the total charge on the spheres is conserved
   (c) both the total energy and charge are conserved
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