Question

Given below are two statements :
Statement I : Most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus and the electrons revolve around it, is Rutherford’s model.
Statement II : An atom is a spherical cloud of positive charges with electrons embedded in it, is a special case of Rutherford’s model.
In the light of the above statements, choose the most appropriate from the options given below.

• A. Both statement I and statement II are false
• B. Statement I is false but statement II is true
• C. Statement I is true but statement II is false
• D. Both statement I and statement II are true

Answer 1

The Correct Option is C

To answer this question, we need to assess the given statements in the context of historical atomic models.

Statement I: "Most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus and the electrons revolve around it, is Rutherford’s model." 

• This description accurately represents Rutherford's model of the atom, which proposed that an atom consists of a small, dense nucleus containing the majority of the atom's mass and all of its positive charge. Electrons are located outside the nucleus and revolve around it in orbits. This model was developed based on the gold foil experiment, which showed deflection of alpha particles, suggesting the presence of a concentrated positive core.
• Hence, statement I is true.

Statement II: "An atom is a spherical cloud of positive charges with electrons embedded in it, is a special case of Rutherford’s model."

• This statement actually describes the Thomson model of the atom, commonly known as the "plum pudding model", where the atom is envisioned as a sphere of positive charge with negatively charged electrons dotted throughout, like plums in a pudding.
• Rutherford's model, on the other hand, was a significant departure from this view as it introduced the concept of a central nucleus. Thus, Rutherford's model cannot be considered a special case or derivative of Thomson's model.
• Hence, statement II is false.

Given the analysis above, the correct choice is: Statement I is true but statement II is false.

Answer 2

• According to Rutherford’s atomic model, most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus, and the electrons revolve around it.
• According to Thomson’s atomic model, the atom is a spherical cloud of positive charge with electrons embedded in it.
• Hence: - Statement I is true as per Rutherford’s model. - Statement II is false because it is Thomson’s model, not Rutherford’s.

The Correct Answer is: Statement I is true but statement II is false