For the following halides: $(1) \ BCl_3$,$(2) \ AlCl_3$,$(3) \ GaCl_3$,$(4) \ InCl_3$,what is the decreasing order of their Lewis acid strength?

Which of the following statements is correct regarding boron hydrides?

Two elements $X$ and $Y$ combine separately with a highly electropositive metal to form binary compounds,which upon hydrolysis yield borane and silane,respectively. What are $X$ and $Y$?

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:

Aluminium hydroxide is soluble in excess of sodium hydroxide forming the ion

Group-$13$ elements react with $O_2$ to form oxides of the type $M_2O_3$ ($M =$ element). Which among the following is the most basic oxide?