Periodic Properties Test - 5

The valency first increases from 1 to 4 (IA to VIA) and then, decreases from a (4 to 1) VA to VII A.

B < C < N < O is not the correct increasing order of of the first ionization energies.
Although the ionization energies increase across the period, but the ionization energy of nitrogen is more than that of oxygen. This is because of the stable configuration of half filled p-orbitals in nitrogen.

A cation is always smaller than the parent atom. Therefore, size of Al will be larger than that of its ion.

Anions are always larger than their parent atoms and also, than their cations.

On moving across the period the effective nuclear charge increases and consequently the atomic radius decreases.
Alkali metals have the largest value of atomic radius in their respective periods.
The elements of period III are: Na, Mg, Al, Si, P, S, Cl, Ar
Hence, sodium has the largest atomic radius in period III.

Ionisation energy increases with increase in the penetration power of the orbitals as the ionization energy is higher for the electron which is closer to the nucleus and experiences a stronger nuclear pull.
s-orbital,owing to its spherical shape has the maximum penetration followed by p, d and f orbitals
Hence the order of the ionization energies of the orbitals is the same as the penetration power of the orbitals.
s > p > d > f

The third ionisation potential is much larger than the second. It implies that the element aquires a noble gas configuration after the loss of two electrons.
Hence, the element can be Mg.

The ionisation energy values for valence electrons are comparable. Any quantum jump in the successive ionization energy values indicates that a stable configuration was acquired in the initial step. Among the given values, the biggest jump is between IE₄ and IE₅. Hence, there are four valence electrons for an atom of 'X' and removal of those electrons imparts the stable configuration of a noble gas to the element.