12.1 Choose the correct alternative from the clues given at the end of each statement:

(a) The size of the atom in Thomson’s model is .......... the atomic size in Rutherford’s model. (much greater than/no different from/much less than.)

(b) In the ground state of .......... electrons are in stable equilibrium, while in .......... electrons always experience a net force. (Thomson’s model/ Rutherford’s model.)

(c) A classical atom based on .......... is doomed to collapse. (Thomson’s model/ Rutherford’s model.)

(d) An atom has a nearly continuous mass distribution in .......... but has a highly non-uniform mass distribution in .......... (Thomson’s model/ Rutherford’s model.)

(e) The positively charged part of the atom possesses most of the mass in .......... (Rutherford’s model/both the models.)

Hint: Recall Thomson's model and Rutherford's model of an atom.
(a)
Step 1:
Compare the size of the atom in both models.
The sizes of the atoms taken in Thomson's model and Rutherford's model have the same order of magnitude.
(b)
Step 2: Identify the state of equilibrium of an atom in both models.
In the ground state of Thomson's model, the electrons are in stable equilibrium. However, in Rutherford's model, the electrons always experience a net force.
(c)
Step 3: Find drawbacks of Rutherford's model.
Rutherford's model didn't mention the arrangement of electrons. So, a classical atom based on Rutherford's model is doomed to collapse.
(d)
Step 4: Compare mass distribution in both models.
An atom has a nearly continuous mass distribution in Thomson's model but has a highly non-uniform mass distribution in Rutherford's model.
(e)
Step 5: Find the mass distribution in Rutherford's model of an atom.
The positively charged part of the atom possesses most of the mass in both models.