Look at the diagram below. The ammonium hydroxide moves down the tube. What process causes this movement?

The movement of ammonium hydroxide down the tube is primarily caused by the process of diffusion. Here are the key points explaining this process:

1. Diffusion: This is the net movement of molecules from an area of higher concentration to an area of lower concentration. In a solution, particles naturally spread out over time.

2. Concentration Gradient: The ammonium hydroxide moves down the tube because it is likely moving from a region with a higher concentration (where it was initially placed) to a region with a lower concentration (further down the tube).

3. Factors Influencing Movement: Temperature, pressure, and the nature of the medium can affect the rate of diffusion, but the fundamental principle remains the same: particles move to achieve equilibrium.

In summary, the movement of ammonium hydroxide down the tube is a result of diffusion, driven by the concentration gradient.