Which of the following is used as a moderator in nuclear reactor?
A. Graphite
B. Uranium
C. Cadmium
D. Boron
Answer: Option A
Solution (By JKSSB Mock Tests)
Graphite, heavy water (D₂O), beryllium are moderators. Cadmium and boron are control rods (absorb neutrons). Uranium is fuel. Moderator slows neutrons.
Explanation:
Dispersion: red has longest wavelength, lowest refractive index, deviates least. Violet deviates most. So spectrum: red at top (least deviation), violet at bottom.
Explanation:
Though the ship is made of iron, it is hollow inside and traps a large volume of air. This makes the overall or average density of the ship less than the density of water. According to the law of floatation, an object floats if its average density is less than that of the fluid. A solid iron needle has a higher density than water, so it sinks.
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