Question

The basic character of the transition metal monoxides follows the order: (Atomic no. - Ti = 22, V = 23, Cr = 24, Fe = 26)

• A. VO > CrO > TiO > FeO
• B. CrO >VO > FeO > TiO
• C. TiO > FeO > VO > CrO
• D. TiO > VO > CrO > FeO

Hint:

Transition metals belong to the d-block of the periodic table. In these elements, the last electron goes to the d orbital.

Answer 1

The Correct Option is D

The question tests the understanding of the basicity of transition metal monoxides. When comparing the basic character of transition metal oxides, it's essential to look at the metallic oxidation state and the ionic radius. These factors play a crucial role in determining the nature of the oxide, whether it's basic, amphoteric, or acidic. 

1. Understanding the Electronic Configuration and Oxidation State: 
   • Titanium (Ti), with atomic number 22: TiO contains Ti in +2 oxidation state.
   • Vanadium (V), with atomic number 23: VO contains V in +2 oxidation state.
   • Chromium (Cr), with atomic number 24: CrO contains Cr in +2 oxidation state.
   • Iron (Fe), with atomic number 26: FeO contains Fe in +2 oxidation state.
2. Relation of Oxidation State and Basic Character:
   • The basic character of the oxides generally increases with a decrease in oxidation state and a decrease in the number of vacant d-orbitals.
   • Among the given options, with similar oxidation states (+2) and increasing atomic numbers, the relative size, decreasing effective nuclear charge, and electron configuration will influence basicity.
3. Order of Basic Nature:
   • Titanium dioxide (TiO) is relatively more basic because of its larger ionic radius and lower effective nuclear charge than others.
   • Vanadium monoxide (VO) follows, as it is less basic than TiO but more basic than CrO and FeO.
   • Chromium monoxide (CrO) is less basic than VO but more basic than FeO.
   • Iron monoxide (FeO) is the least basic due to its smaller ionic radius and higher effective nuclear charge among these monoxides.

Therefore, the basic character of these transition metal monoxides in decreasing order is:

TiO > VO > CrO > FeO

Thus, the correct option is:

TiO > VO > CrO > FeO