Which one of the following molecular hydrides acts as a Lewis acid?

Which one of the following statements is not correct?

The number of neutrons present in the more abundant isotope of boron is $x$. Amorphous boron upon heating with air forms a product,in which the oxidation state of boron is $y$. The value of $x+y$ is ...

The total number of acidic oxides from the following list is: $NO$,$N_2O$,$B_2O_3$,$N_2O_5$,$CO$,$SO_3$,$P_4O_{10}$

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

Write reactions to justify the amphoteric nature of aluminium.