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Nuclei — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsNuclei1 Mark
Question
For question, statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a) (b) (c) and (d) as given below.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is NOT the correct explanation of A.
  3. A is true, but R is false.
  4. A is false and R is also false.
Assertion (A): Cadmium rods, used in a nuclear reactor, control the rate of fission. Reason (R): Cadmium rods, used in a nuclear reactor, control the rate of fission.
✓

Answer

  1. A is true, but R is false.
Explanation:

Cadmium rods are used in a nuclear reactor to control the rate of fission. The cadmium rods do not slow down or speed up the neutrons produced in a fission reaction of $^{235}U$. Instead, they absorb the neutrons, thereby regulating the power level of the reactor.

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