Question

Arrange $BeC{l_2},MgC{l_2},CaC{l_2},SrC{l_2}$and $BaC{l_2}$according to their increasing tendency of hydrolysis:
A. $BaC{l_2} < SrC{l_2} < CaC{l_2} < MgC{l_2} < BeC{l_2}$
B. $SrC{l_2} < BaC{l_2} < CaC{l_2} < MgC{l_2} < BeC{l_2}$
C. $BaC{l_2} < SrC{l_2} < CaC{l_2} < BeC{l_2} < MgC{l_2}$
D. $BeC{l_2} < MgC{l_2} < CaC{l_2} < SrC{l_2} < BaC{l_2}$

Answer 1

The tendency of hydrolysis is the tendency of ions of the elements to form covalent bonds with a hydroxide ion from water. The tendency of hydrolysis or tendency of ions of elements to form covalent bond with hydroxide ion from water depend upon the hydration radius of that element

Complete step by step answer:
Given compounds- $BeC{l_2},MgC{l_2},CaC{l_2},SrC{l_2},BaC{l_2}$
The tendency of hydrolysis is the tendency of ions of the elements to form covalent bonds with a hydroxide ion from water. The tendency of hydrolysis or tendency of ions of elements to form covalent bond with hydroxide ion from water depend upon the hydration radius of that element
$Tendency{\rm{ }}\,of{\rm{ }}\,hydrolysis$ $\propto$ $Hydration{\rm{ }}\,radius$…………………………………………………………………………… (I)
Hydration radius gives the measure of capacity of energy that can be liberated when an ion gets hydrated. In a group, the hydration radius of elements decreases as we move from top to the bottom.
And hydration radius is inversely proportional to the size of ions.
$Hydration\,{\rm{ }}radius\,$ $\propto$ $\dfrac{1}{{size}}$…………………………………………………………………………………………………………... (II)
So from equation (I) and (II) the tendency of hydration is inversely proportional to the size of ions.
$Tendency\,{\rm{ }}of\,{\rm{ }}hydrolysis$ $\propto$ $\dfrac{1}{{size}}$………………………………………………………………………………………………. (III)
The size of barium ion = $268pm$
The size of strontium ion = $231pm$
The size of calcium ion = $200pm$
The size of magnesium ion = $173pm$
The size of Beryllium ion = $112pm$
Hence, we can arrange them according to the increasing tendency of hydrolysis:
$BaC{l_2} < SrC{l_2} < CaC{l_2} < MgC{l_2} < BeC{l_2}$

Note:
Tendency of hydration is inversely proportional to the size of ions. Hydration radius gives the measure of capacity of energy that can be liberated when an ion gets hydrated. In a group, the hydration radius of elements decreases as we move from top to the bottom.