Question

The decreasing order of the ionisation potential of the following elements is

• A. $Ne>Cl>P>S>Al>Mg$
• B. $Ne>Cl>P>S>Mg>Al$
• C. $Ne>Cl>S>P>Mg>Al$
• D. $Ne>Cl>S>P>Al>Mg$

Answer 1

Answer: (B)

Ionisation energy increases from left to right in a period but ionisation energy ${}_{\text{group- }-2}>$ ionisation energy ${}_{\text{group }-13}$ and ionisation energy ${}_{\text{group- }-15}>$ ionisation energy ${}_{\text{group- }16}$ This is because of stable electronic configuration of group $2\left(n{s}^2\right)$ and group $15\left(n{s}^{2}n{p}^3\right)$.

Thus, $Ne>Cl>P>S>Mg>Al$ : Ionisation potential