Which of the following structures is similar to graphite?

In the structure of borax,the numbers of boron atoms and $B-O-B$ units,respectively,are

Which of the following pairs contains structurally similar substances?

Which element belongs to the family of elements that also includes the element gallium?

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$
$H_4\underline{B}_2O_5 + H_2O \longrightarrow H_3BO_3$

The correct formula of borax is $Na_2[B_4O_5(OH)_4] \cdot 8H_2O$. If the formula is represented as $Na_2[B_4O_5(OH)_x] \cdot yH_2O$, then the sum of $x$ and $y$ is: