Question

Which of the alkali metal chloride $\left(MCl\right)$ forms its dihydrate salt $\left(MCl.2H_{2}O\right)$ easily ?

• A. $CsCl$
• B. $RbCl$
• C. $LiCl$
• D. $KCl$

Answer 1

The correct option is C $LiCl$

Amongst alkali metals, chloride salts of lithium are hydrated. Other alkali metals form anhydrous chloride. This is because lithium ion has smallest size due to which it has the strongest polarizing power amongs alkali metal ions. This makes water molecules attach to lithium salt and form a crystal called water of crystallization.
This tendency decreases down the group as the alkali metal becomes larger in size.

Hence, option (a) is correct.