Draw the structure of boric acid showing hydrogen bonding. Which species is present in water ? What is the hydridisation of boron in this species ?

Explanation

Orthoboric acid `H_(3)BO_(3)`, in solid state possesses a layer structure made up of `B(OH)_(3)` units forming hexagonal rings of H-bonding as given below

Each H-atom acts as a bridge between two oxygen atoms of different `BO_(3)^(3-)` units
Boric acid when dissolved in water, acts as Lewis acid forming `B(OH)_(4)^(-)`
`H_(3)BO_(3)+H_(2)O rarr B(OH)_(4)^(-)+H^(+)`
The hybridisation of boron in `B(OH)_(4)^(-)` is `sp^(3)`