There are TWO atoms in one molecule of hydrogen.
Nitrogen is a non-metal and aluminum is a metal so the bond would be ionic.
Answer : At constant pressure work is done by the system on the surroundings.
Explanation :
Work done : Any quantity that flows across the boundary of a system during a change in its state and it completely convertible into the lifting of a weight in the surroundings.
Formula for work done is:

Sign convention :
- When volume expand then system work that means work done by the system.
w = (-ve)
- When volume compress then surrounding work that means work done on the system.
w = (+ve)
The given reaction is:

This is a evaporation process in which phase changes from liquid state to gaseous state at constant temperature.
At constant pressure, work depends only on volume.
In evaporation process, the volume expand that means work is done by the system on the surroundings.
Sign convention is, w = (-ve)
Thus, at constant pressure work is done by the system on the surroundings.
Answer:
There's no passage but I can say that matter are that ''thing'' which extend through all Universe, matter is everything. It can be seen or felt as liquid, gas or solid. This changes of its state depend on the amount of energy that is involved.
So, here is used categorical thinking because is a abstract concept that is hard to understand sometimes. It's abstract when we say that matter is all, not just what we see, but even what we don't see like ''Dark Matter'', which is the majority in the Universe.