Concept:Down Group II (alkaline earth metals), atomic size increases and this controls the trends of ionization energy, melting point, shielding effect, and electronegativity.
Explanation:Going down Group II, each element has an additional electron shell.
This makes the atomic radius larger.
The inner shells provide greater shielding of the outermost electrons from the nucleus.
So the shielding effect increases down the group, not decreases.
Because the outer electrons are held less tightly, ionization energy decreases down the group.
The increased atomic size and shielding also lower the electronegativity down the group.
In metals, larger atoms mean the delocalized electrons are farther from the positive ions.
This weakens the metallic bond.
Therefore, the melting point normally decreases down Group II, not increases.
All the given options state trends that are opposite to the correct behaviour.
Answer:None of the given options is correct. Down Group II, ionization energy decreases, melting point decreases, shielding effect increases, and electronegativity decreases.