Each element is diffrent than another element
Reactivity is the name your looking for I believe.
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:
the fuel efficiency in kilometers per liter is 16.561 kilometer per liter
Explanation:
The computation of the full efficiency in kilometers per liter is shown below:
39.0 miles ÷ gallon = (39.0 miles ÷ gallon) × (1.6094 km ÷ 1 miles) × (1 gallon ÷ 3.79 L)
Now cut the opposite miles and gallons
So, the fuel efficiency would be
= 16.561 kilometers per liter
Hence, the fuel efficiency in kilometers per liter is 16.561 kilometer per liter