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Nuclei — Physics STD 12 Science — Question

Rajasthan 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): There is a chain reaction when uranium is bombarded with slow neutrons. Reason (R): When uranium is bombarded with slow neutrons, more neutrons are produced.
✓

Answer

  1. Both A and R are true, and R is the correct explanation of A.
Explanation:
When uranium is bombarded by slow neutrons the reaction is represented as $_{92}^{235}\text{U}+\ _0^1\text{n}\rightarrow\ _ {56}^{141}\text{Ba}+\ _{36}^{92}\text{kr}+\ 3_0^1\text{n}+\text{Energy}$
As more neutrons are produced, the reason is correct. These additional neutrons strike other uranium nuclei to produce even more neutrons. Thus a chain reaction is established.

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