Question

Following conclusions were drawn from the given figure :
I. There is a positively charged centre in an atom called the nucleus.
II. An atom consists of a positively charged sphere and the electrons are embedded in it.
III. The electrons revolve around the nucleus in well-defined orbits.
IV. The size of the nucleus is very small as compared to the size of the atom
V. Only certain special orbits known as discrete of electrons are allowed inside the atom.
Choose the correct statements.

• A. I, II and III
• B. II, III and V
• C. I, III and IV
• D. All of these

Answer 1

Answer: (C)

I, III and IV

On the basis of scattering experiments, Rutherford proposed the model of an atom, which is known as the nuclear atomic model. According to this model -
(i) An atom consists of a heavy positively charged nucleus where all the protons are present.
(ii) The volume of the nucleus is very small and is only a minute fraction of the total volume of the atom.
There is empty space around the nucleus called the extranuclear part. In this part electrons are present. The no. of electrons in an atom is always equal to no. of protons present in the nucleus. As the nuclear part of the atom is responsible for the mass of the atom, the extranuclear part is responsible for its volume.
Electrons revolve around the nucleus in closed orbits with high speeds.