Which type of solution can scatter light, thereby demonstrating the Tyndall effect?

The type of solution that can scatter light and demonstrate the Tyndall effect is indeed a colloid. A colloid is a mixture where tiny particles of one substance are distributed evenly throughout another substance. These particles are larger than those found in a true solution but are not large enough to settle out or be seen individually by the naked eye. When light passes through a colloid, the larger particles can scatter the light, creating the Tyndall effect, which is visible as a beam of light shining through the medium.

For comparison, a true solution consists of solute particles that are so small that they do not scatter light, thus the Tyndall effect is not observed in these solutions. Suspensions contain larger particles than colloids and can also scatter light, but they are typically not stable over time and will settle out due to gravity. Crystalline substances refer to solids with a well-defined structure and do not exhibit the Tyndall effect in a typical context of mixed solutions. Thus, the correct identification of the colloid highlights its unique property of scattering light.