In thistle funnel experiment

Options

A. Water potential in thistle funnel first decreases and then increases
B. Water potential in thirstle funnel first increases and later decreases
C. Water potential in the beaker initially increase and later decreases
D. Water potential in the beaker initially decreases

Answer

### Step-by-Step Solution for the Thistle Funnel Experiment

1. **Understanding the Thistle Funnel Setup**:
- A thistle funnel is a laboratory apparatus used to demonstrate osmosis.
- It consists of a funnel with a long stem that is submerged in a beaker of pure water.
- The funnel is filled with a sugar solution, and there is a semi-permeable membrane between the sugar solution and the pure water.

2. **Initial Conditions**:
- The sugar solution in the thistle funnel has a higher solute concentration compared to the pure water in the beaker.
- The initial level of the sugar solution is noted.

3. **Osmosis Process**:
- Osmosis is the movement of water from an area of lower solute concentration (pure water) to an area of higher solute concentration (sugar solution) through a semi-permeable membrane.
- As water enters the thistle funnel from the beaker, the volume of the sugar solution increases.

4. **Water Potential Changes**:
- Initially, as water enters the funnel, the water potential in the thistle funnel decreases because the concentration of solutes (sugar) increases.
- As more water continues to enter, the hydrostatic pressure builds up in the funnel, which eventually leads to a point where the osmotic pressure and hydrostatic pressure balance out.

5. **Equilibrium**:
- The process continues until equilibrium is reached, meaning the osmotic pressure (due to the sugar solution) equals the hydrostatic pressure (due to the water entering).
- At this point, the water potential in the thistle funnel begins to increase as the influx of water stabilizes.

6. **Conclusion**:
- Therefore, the correct statement regarding the water potential in the thistle funnel is that it first decreases (as water enters and dilutes the sugar solution) and then increases (as equilibrium is reached).

### Final Answer:
The correct option is: **Water potential in the thistle funnel first decreases and then increases.**

---