(a)[2]
Explain why boron nitride has a high melting point. Use Fig. 6.1.
(b)[1]
Explain why hydrazine is a poor electrical conductor. Use Fig. 6.1.
(c)[1]
Complete Fig. 6.2 so that it shows the dot-and-cross diagram for the electronic configuration of hydrazine. Include only outer-shell electrons.
(d(i))[1]
Deduce the oxidation number of nitrogen in $\text{NH}_3$.
(d(ii))[1]
Explain why this is not a redox reaction by referring to nitrogen's oxidation number.
(e)[3]
Show by calculation that boron oxide is in excess when $8.0\text{ g}$ of $\text{B}_2\text{O}_3$ reacts with $7.2\text{ g}$ of magnesium in the reaction $\text{B}_2\text{O}_3+3\text{Mg}\rightarrow2\text{B}+3\text{MgO}$.