Atomic Structure 1 Question 25

1. Which one of the following about an electron occupying the 1s-orbital in a hydrogen atom is incorrect? (The Bohr radius is represented by a0 )

(2019 Main, 9 April II)

(a) The electron can be found at a distance 2a0 from the nucleus.

(b) The magnitude of the potential energy is double that of its kinetic energy on an average.

(c) The probability density of finding the electron is maximum at the nucleus.

(d) The total energy of the electron is maximum when it is at a distance a0 from the nucleus.

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Answer:

Correct Answer: 1. (d)

Solution:

  1. Statement (d) is incorrect. For 1s-orbital radial probability density (R2) against r is given as:

For 1s-orbital, probability density decreases sharply as we move away from the nucleus.

The radial distribution curves obtained by plotting radial probability functions vsr for 1s-orbital is

The graph initially increases and then decreases. It reaches a maximum at a distance very close to the nucleus and then decreases. The maximum in the curve corresponds to the distance at which the probability of finding the electron in maximum.