A white crystalline solid A dissolves in water to give an alkaline solution . On heating A first loses water molecules and swells up . On further heating it turns into a transparent liquid which solidifies into a glossy bead . Name it.

Explanation

A is Borax i.e., `Na_(2) [B_(4)O_(5)(OH)_(4)].8H_(2)O` which is also written as `Na_(2)B_(4)O_(7).10H_(2)O` The reactions are as follows :
`Na_(2)B_(4)O_(7)+7H_(2)O rarr underset("Alkaline")(2NaOH)+underset("Orthyoboric acid")(4H_(3)BO_(3))`
On heating :

`Na_(2)B_(4)O_(7).10H_(2)Ooverset("heat ")rarr Na_(2)B_(4)B_(4)O_(7) overset("heat ")rarr underset("Transparent glossy bead")underset("Sodium metaborate ")(2NaBO_(2)+B_(2)O_(3))`