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Atoms — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsAtoms1 Mark
Question
For question two 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): The force of repulsion between atomic nucleus and $\alpha$-particle varies with distance according to inverse square law.
Reason (R): Rutherford did $\alpha$-particle scattering experiment.
✓

Answer

  1. Both A and R are true, but R is NOT the correct explanation of A.
Explanation:
In Rutherford'$\alpha$-particle scattering experiment, some of $\alpha$-particles were found to be scattered at very large angles inspite of having very high kinetic energy. This shows that there are $\alpha$-particles which will be passing very close to nucleus. Rutherford confirmed the repulsive force on $\alpha$-particles due to nucleus varies with distance according to inverse square law and that the positive charges are concentrated at the centre and not distributed throughout the atom. This is the nuclear model of Rutherford.

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