Question

Which of the following order is not correct :-

• A. $CrO < Cr _{2} O _{3}< CrO _{3}$ (covalent character)
• B. $ZnO$ (Philosopher's wool) $> ZnS ($ Zinc blend $)$ (ionic character)
• C. $BeCl _{2}> MgCl _{2}> CaCl _{2}> SrCl _{2}> BaCl _{2}$ (ionic character)
• D. $KCl < AgCl$ (covalent character)

Answer 1

Answer: (C)

(i) $Cr ^{+2} O , Cr _{2}^{+3} O _{3}, Cr ^{+6} O _{3}$

oxidation state of metal $\uparrow$
polarisation $\uparrow$
covalent character $\uparrow$
(ii) $ZnO \left( O ^{-2}\right), ZnS \left( S ^{-2}\right)$

anionic size $\uparrow$, polarisation $\uparrow$,
covalent character $\uparrow$, ionic character $\downarrow$
(iii) $BeCl _{2} \,\,MgCl _{2} \,\,CaCl _{2} \,\,SrCl _{2}\,\, BaCl _{2}$

(cationic size $\uparrow$, polarisation $\downarrow$, ionic character $\uparrow$ )
(iv) $KCl \quad AgCl$
$K ^{+} \rightarrow$ inert gas configuration cation
$Ag ^{+} \rightarrow$ Pseudo inert gas configuration cation polarisation power order $\rightarrow K ^{+}< Ag ^{+}$