Celery stalks that are immersed in fresh water for several hours become stiff. similar stalks left in a 0.15 m salt solution become limp. from this we can deduce that the fresh water

From this it can be deduced that the fresh water is hypotonic and the salt solution is hypertonic to the cells of the celery stalks.

Explanation:

When submerged in water, the celery stalks become stiff and hard, this shows that water moves within the stalk, thus, water is hypotonic in comparison to the celery stalk. Therefore, water moves from the region of higher concentration to the region of lower concentration.  

When the same celery stalk is administered into the 0.15 M solution it turns soft, which shows that water from the celery stalk moves out. Thus, the salt solution is hypertonic in comparison to the celery stalk. Therefore, freshwater is hypertonic and the solution of salt is hypertonic to the celery stalk cells.  

i'll try what topic lol