Which of the following compounds is formed as a blue bead when borax is heated with cobalt oxide?

Give uses of Borax.

Which element of group $13$ does not show the group valency in its compounds?

The reaction of $H_{3}N_{3}B_{3}Cl_{3}$ $(A)$ with $LiBH_{4}$ in tetrahydrofuran gives inorganic benzene $(B)$. Further,the reaction of $(A)$ with $(C)$ leads to $H_{3}N_{3}B_{3}(Me)_{3}$. Then,compounds $(B)$ and $(C)$ respectively,are

Which one of the following metallic oxides exhibits amphoteric nature?

Match the following compounds in List-$I$ with their uses in List-$II$:

List-$I$ (Compounds)	List-$II$ (Uses)
$A$. Boron-$10$	$I$. Antiseptic
$B$. Borax	$II$. Bullet proof vest
$C$. Boron-fibre	$III$. Neutron absorber
$D$. Orthoboric acid	$IV$. Heat resistance glasses