Structure of the Atom

An atom with 3 protons and 4 neutrons will have a
valency of

The electron distribution in an aluminium atom is

Which of the following statement is always correct ?

Atomic models have been improved over the years.
Arrange the following atomic models in the order
of their chronological order
(i) Rutherford's atomic model
(ii) Thomson's atomic model
(iii)Bohr's atomic model

Which of the following correctly represent the
electronic distribution in the Mg atom ?

Rutherford's alpha (a) particles scattering
experiment resulted into discovery of