Answer:
+5
Explanation:
You use the rules for oxidation numbers to calculate that the oxidation number of N is +5.
Answer: The excess amount changes from a gas into a liquid or solid (ice). The process of water changing from a gas to a liquid is called "condensation," and when gas changes directly into a solid, it is called "deposition." These two processes are how clouds form.
Typically Aluminum Oxide is used for sandpaper or a cheaper alternative for industrial diamond.