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Karnataka Board PUCPUC Science 2nd PUC Class 12

The radius of the innermost electron orbit of a hydrogen atom is 5.3 × 10−11 m. What are the radii of the n = 2 and n = 3 orbits?

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Question

The radius of the innermost electron orbit of a hydrogen atom is 5.3 × 10−11 m. What are the radii of the n = 2 and n = 3 orbits?

Numerical
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Solution

The radius of the innermost orbit of a hydrogen atom, r1 = 5.3 × 10−11 m

Let r2 be the radius of the orbit at n = 2. It is related to the radius of the innermost orbit as:

r2 = (n)2r1

= (2)2 × 5.3 × 10−11

= 4 × 5.3 × 10−11

= 2.12 × 10−10 m

For n = 3, we can write the corresponding electron radius as:

r3 = (n)2r1

= (3)2 × 5.3 × 10−11

= 9 × 5.3 × 10−11

= 4.77 × 10−10 m

Hence, the radii of an electron for n = 2 and n = 3 orbits are 2.12 × 10−10 m and 4.77 × 10−10 m, respectively.

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Chapter 12: Atoms - EXERCISES [Page 305]

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NCERT Physics Part I and II [English] Class 12
Chapter 12 Atoms
EXERCISES | Q 12.7 | Page 305
NCERT Physics Part I and II [English] Class 12
Chapter 12 Atoms
Exercise | Q 12.8 | Page 436

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