In his calculations, Bohr came across a number now called the ...

[Capo]

In his calculations, Bohr came across a number now called the Bohr radius. This number is 5.29 X 10^-11 m and is
  A. The maximum radius of the hydrogen atom.
  B. The minimum radius of the hydrogen atom.
  C. The average radius of the hydrogen atom.
  D. The minimum radius of atoms of all elements.
  E. The maximum radius of atoms of all elements.

Question 2

The planetary model of the atom was fundamentally flawed. It failed theoretically because
 

A. a perfectly circular orbit would violate the laws of gravitation.
  B. electrostatic attraction would not be sufficient to keep the electron/nucleus in a bound state.
  C. it predicted positive and negative charge equally distributed throughout the atom.
  D. it was well established experimentally that accelerating electrons emit electromagnetic radiation.
  E. it did not provide for the existence of neutrons.

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Answer to Question 1

B.
The Bohr radius gives the minimum radius of the hydrogen atom. This minimum radius is the smallest radius of the atom because it describes the radius of the ground state, or the most tightly bound state of the atom.

Answer to Question 2

An electron orbiting a nucleus in a circular orbit would be under constant accelerationthe direction of velocity changesand would constantly emit radiation. The electron would continuously lose energy and quickly fall into the nucleus.
D.

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