The valency of sulphur is

The valency of neon is

In  Al, the number of neutrons are

The number of nucleons is the

The …… isotope is used in the treatment of goitre.

Which of the following is an example of isotopes ?

The mass of neutron is nearly equal to that of ……

According to Thomson, the total …… of the atom is uniformly distributed throughout the atom.

Rutherford allowed the alpha particles to pass through …… in his alpha particles scattering experiment.

Alpha particles do not have ……

According to Bohr’s model, electrons revolve around nucleus in ……

If n = 3, it represents the …… shell.

According to Rutherford, the mass of the atom is concentrated at ……

Electrons must …… energy to move to a higher energy level.

Electrons must …… energy to move to a lower energy level.