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.
Physical change because ther is force which is the electric current
Explanation:
NaCl, HCl, NaOH, KCl, CH3COOH
Answer:
B.
Explanation:
Everything else is not a drawback, it is a benefit.
Answer:
AgNO2
Explanation:
The question asks to know which of these two insoluble salts is expected to be more soluble in acidic solution than in pure water.
To answer this question specifically, we need to know if the anions contained in the insoluble salt is a conjugate of a weak acid or that of a weak base.
Generally, the solubility of insoluble salts that contain anions which are conjugates of weak acids increases in the presence of an acidic solution than in water. While, the solubility of insoluble salts that contain anions which are conjugates of strong acids decreases in the presence of an acidic solution.
Having said this, AgNO2 contains NO2 which is the conjugate base of the Trioxonitrate iii acid which is a weak acid. Hence, it is expected to be stronger in acidic solution than in water.