Question

In the periodic table of the elements, the phrase “middle row anomaly” refers to:

• A. Instability of halogen oxides
• B. Stability of alkali metal oxides
• C. Stability of transition metal oxides
• D. Both (A) and (C)

Answer 1

The correct option is D

Both (A) and (C)

Explanation for Correct answer:-

Option (D)- Both (A) and (C)

Halogen oxides:-

1. The Halogen oxides are key species in the catalytic cycles.
2. The Halogen oxides radicals are$\mathrm{XO},\mathrm{where}\mathrm{X}=\mathrm{Cl},\mathrm{Br},\mathrm{I}$.

Transition metal oxides:-

1. These are the compounds that are composed of Oxygen atoms bound to transition metals from d-block and have partially filled d-sub-shell.
2. They are commonly utilized for their catalytic activity.

Middle row anomaly:-

1. In the periodic table, the elements ${\mathrm{Br}}_2\mathrm{O},{\mathrm{BrO}}_{2,}{\mathrm{BrO}}_3$ are the least stable halogen oxides.
2. These elements only exist at low temperatures due to the transition metal contraction which is the change in the atomic radius trend that the d block elements experience.

Therefore, the phrase “middle row anomaly” refers to the “Instability of halogen oxides” and “Stability of transition metal oxides”, option (D):- Both (A) and (C).