When orthoboric acid $({H_3}B{O_3})$ is heated, the residue left is

Boric acid is an acid because its molecule 

Which of the following is correct

Given below are two statements:

Statement $I$ : The decrease in first ionization enthalpy from $B$ to $Al$ is much larger than that from $Al$ to $Ga$.

Statement $II$ : The d orbitals in Ga are completely filled.

In the light of the above statements, choose the most appropriate answer from the options given below

Give reasons:

$(i)$ Conc. $HNO _{3}$ can be transported in aluminium container.

$(ii)$ $A$ mixture of dilute $NaOH$ and aluminium pieces is used to open drain.

$(iii)$ Graphite is used as lubricant.

$(iv)$ Diamond is used as an abrasive.

$(v)$ Aluminium alloys are used to make aircraft body.

$(vi)$ Aluminium utensils should not be kept in water overnight.

$(vii)$ Aluminium wire is used to make transmission cables.

Which of the following structure is similar to graphite ?