Question

The first ionization energy of magnesium is smaller as a compound to that of elements X and Y but higher than that of Z. The elements X, Y, and Z, respectively are:

• A. Argon, Lithium, and Sodium
• B. Chlorine, Lithium, and Sodium
• C. Neon, Sodium, and Chlorine
• D. Argon, Chlorine, and Sodium

Answer 1

The correct option is D

Argon, Chlorine, and Sodium

Explanation of the correct option:

The correct answer is option D:

The order of first ionization enthalpy of the 3rd period is,

$\mathrm{Na}<\mathrm{Al}<\mathrm{Mg}<\mathrm{Si}<\mathrm{S}<\mathrm{P}<\mathrm{Cl}<\mathrm{Ar}$

Thus, the elements X and Y are Argon and Chlorine.
And, element Z is Sodium.

Explanation of the incorrect options:

Options A, B, and C:

1. Using the order of first ionization enthalpies of the 3rd-period elements, the elements X, Y, and Z are found to be Argon, Chlorine, and Sodium.
2. Hence, these options are incorrect.

Hence, option D is correct.
The elements X, Y, and Z, respectively are Argon, Chlorine, and Sodium.