1 what's the Tyndall Effect and whats one example of this effect?

2) Given an unknown mixture consisting of two or more substances, how could we determine whether that mixture is a true solution, a colloid, or a suspension?
3) why is a suspension considered a heterogenous mixture?

Smoke is another colloid with the Tyndall effect.

http://silver-lightning.com/tyndall/

Here is something on suspensions.
http://en.wikipedia.org/wiki/Suspension_(chemistry)

1) The Tyndall Effect refers to the scattering of light by colloidal particles or very fine particles suspended in a medium. When a beam of light passes through a medium with dispersed particles, the light gets scattered in different directions, making the path of light visible. This effect is visible when a beam of light passes through fog, mist, or even a glass of milk. The suspended particles in the medium scatter the light, making the beam visible.

2) To determine whether a mixture is a true solution, a colloid, or a suspension, you can perform a few tests:

- Size of particles: A true solution contains dissolved particles that are extremely small, generally less than 1 nanometer in size. A colloid contains smaller particles than a suspension but larger than those found in a true solution. A suspension contains larger particles that can settle down over time.

- Transparency: A true solution is transparent because the dissolved particles are so small that they cannot scatter light significantly. A colloid, on the other hand, appears translucent or slightly opaque due to the scattering of light by the dispersed particles. A suspension is usually opaque due to the presence of larger, visible particles.

- Particle settling: A true solution does not show any settling of particles since the particles are uniformly distributed and do not separate over time. A colloid may show slight settling, but the particles remain dispersed for a longer period. A suspension, however, shows visible settling of particles at the bottom over time.

- Filtration: A true solution cannot be separated by filtration, as the particles are too small to be trapped by a filter. A colloid can be separated by some special techniques like ultrafiltration or dialysis. A suspension can be easily separated by filtration, as the larger particles can be trapped by a filter.

3) A suspension is considered a heterogeneous mixture because it contains visibly distinguishable particles that are dispersed in a medium. These particles are often larger and can settle down due to gravity over time. Unlike a homogeneous mixture, where the components are uniformly mixed and not distinguishable to the naked eye, a suspension shows a non-uniform distribution of particles. The visible separation of particles in a suspension makes it heterogeneous.