In the borax bead test,which of the following compounds is formed?

Inorganic graphite is:

Two students were given the task to prepare an adduct $NH_3 \to BH_3$ at low temperature :-
Student $I$ :- She mixed $B_2H_6$ and $NH_3$
Student $II$ :- He mixed $B_2H_6$ with $THF$ followed by addition of $NH_3$
Which student is expected to get the $CORRECT$ final product?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Boron is unable to form $BF_{6}^{3-}$.
Reason $R$: Size of $B$ is very small.
In the light of the above statements,choose the correct answer from the options given below.

Given below are two statements :
Statement $I$ : Gallium is used in the manufacturing of thermometers.
Statement $II$ : $A$ thermometer containing gallium is useful for measuring the freezing point $(256 \ K)$ of brine solution.
In the light of the above statement,choose the correct answer from the options given below :

Which of the following statements about $BF_4^{-}$ and $AlF_6^{3-}$ are correct?
$(i)$ $B$ and $Al$ differ in their oxidation states.
$(ii)$ $B$ and $Al$ differ in their covalency.
$(iii)$ $B$ obeys the octet rule.
$(iv)$ $B$ and $Al$ are in diagonal relationship.