Question

Which of the following is the most ionic compound?

• A. $P_2{O}_5$
• B. $Cr{O}_3$
• C. $MnO$
• D. $M{n}_2{O}_7$

Answer 1

The correct option is C $MnO$

Ionic bond is favoured by less charge on ions (according to Fajan's rule).
Here, oxygen has $-2$ oxidation state in all compounds.
A) In $P_2{O}_5$, $P$ has $+5$ oxidation.
B) In $Cr{O}_3$, $Cr$ has $+6$ oxidation state.
C) In $MnO$, $Mn$ has $+2$ oxidation state.
D) In $M{n}_2{O}_7$, $Mn$ has $+7$ oxidation state.
Hence, the least oxidation state exists for $Mn$ in $MnO$. Therefore, it is the most ionic in nature.