Thank you for reporting, we will resolve it shortly
Q.
Among $CaH _{2}, BeH _{2}, BaH _{2}$, the order of ionic character is
Chemical Bonding and Molecular Structure
Solution:
According to Fajan's rule, compounds with small cation, large anion, more charge on cation or anion shows more covalent character. As the above conditions opposes, it shows ionic character. Since, the size of cation decreases in the following order:
$Ba ^{2+}> Ca ^{2+}> Be ^{2+}$
Therefore, the correct order of ionic character will be
$BeH _{2}< CaH _{2}< BaH _{2}$
$BeH _{2}$ has some covalent character. It is because of the effect of polarisation. According to Fajan's rule, smaller the size of cation and more the charge on the cation, greater is its polarising power.
Thus, $BeH _{2}$ has some covalent character also.