Which of the following substances has the least covalent character ?

Options

A. `Cl_(2)O`
B. `NCl_(3)`
C. `PbCl_(2)`
D. `BaCl_(2)`

Answer

D

Explanation

According to Fajan's rule :
Covalent character ` prop ( 1 ) / ( "size of cation") `
` prop ` size of anion
Among the given species order of size of cations
` N^( 3+ ) lt O ^ ( 2 + ) lt Pb ^( 2 + ) lt Ba^( 2 + ) `
order of size of anions ` O^( 2- ) gt Cl^( - ) `
Hence, the order of covalent character is
` NCl_ 3 gt Cl _ 2 O gt PbCl _ 2 gt BaCl _ 2 `
` BaCl _ 2 ` is least covalent in nature.