Which of the following will show Tyndall effect?

Milk

The correct answer is option 1. Milk.

Colloidal particles can easily scatter a beam of visible light. This scattering of a beam of light is called the Tyndall effect.

Milk is an emulsion colloid, and it will show Tyndall effect.

Because of very small particle size in solution, they do not scatter a beam of light passing through the solution. So, the path of light is not visible in a solution.

Salt solution, Copper sulphate solution, Sugar solution are true solutions and do not show Tyndall effect.