You are provided with a mixture of naphthalene and ammonium chloride by your teacher. Suggest an activity to separate them with well labelled diagram.

To separate a mixture of naphthalene and ammonium chloride, you can use the process of sublimation. Sublimation is the process where a solid changes directly to gas without passing through the liquid state. Both naphthalene and ammonium chloride are sublimable substances, but they sublime at different temperatures.

Here are the steps to separate them:

1. Take the mixture in a china dish.
2. Heat the china dish gently. Ammonium chloride sublimes on gentle heating and directly changes from solid to gas. It forms white fumes.
3. The fumes of ammonium chloride can be allowed to pass through a delivery tube into another container where, on cooling, the gas will again form solid ammonium chloride.
4. The naphthalene left behind in the china dish can be scraped out.

Here is a simple diagram:

[Container with mixture] --(heat)--> [China dish with naphthalene] + [Delivery tube] --(cooling)--> [Container with solid ammonium chloride]

Please note that this is a simple text representation. For a well-labelled diagram, you would need to draw this out, labelling the 'Container with mixture', 'China dish with naphthalene', 'Delivery tube', and 'Container with solid ammonium chloride'. Also label the processes of heating and cooling.