Which of the following is the strongest Lewis acid?

Borax is used as a cleansing agent because on dissolving in water it gives:

Give a suitable laboratory preparation method for diborane.

Boric acid,$H_3BO_3$,is a/an ....

$H_3BO_3 + H_2O_2 \to H_2O + 'X' \xrightarrow{NaOH} 'Y'$
Which of the following statements is/are correct for $'Y'$?

Below are two statements,one labeled as Assertion $(A)$ and the other as Reason $(R):$
Assertion $(A)$: Among group $13$ elements,boron's melting point is unusually high $(2453 \ K)$.
Reason $(R):$ Solid boron has a strong crystalline lattice.
In the context of the above statements,choose the correct answer from the following options: