Clouds I believe because hydro means water and clouds are made of water
As you mentioned the question in chemistry so it may be a concentration unit I.e mass per volume.
(SOLUTION)
Mass/volume = total mass/ total volume
Now:
Total mass= 42.95 g
Total volume =351.8mL
Put these values in above equation;
Mass/volume = 42.95/351
“”. = 0.122 g/mL
Answer:
Fairly certain it is the tension of the string
