Draw the structure of $Al_2Cl_6$ and give the uses of $AlCl_3$.

Which of the following is true for an element belonging to group $13$ of the periodic table?

Aluminum dissolves in mineral acids and aqueous alkalis and thus shows amphoteric character. $A$ piece of aluminum foil is treated with dilute hydrochloric acid or dilute sodium hydroxide solution in a test tube and on bringing a burning match stick near the mouth of the test tube,a pop sound indicates the evolution of hydrogen gas. The same activity when performed with concentrated nitric acid,the reaction does not proceed. Explain the reason.

Which of the following statements is/are correct for group $13$ elements?
$A$. $Al$ reacts with dil. $HCl$ to liberate $H_2$ gas
$B$. $Al$ reacts with conc. $HNO_3$ to liberate $H_2$ gas
$C$. Boron reacts with only acids to liberate $H_2$ gas
$D$. Anhydrous $AlCl_3$ reacts with moisture to liberate $H_2$ gas

Which of the following is added to borax to obtain boric acid?

The number of $2$-centre-$2$-electron and $3$-centre-$2$-electron bonds in $B_2H_6$,respectively,are