1. Dissolving and Filtration:

- Add water to the mixture. Salt will dissolve in water, while sulphur powder and sand will remain insoluble.

- Filter the mixture using a filter paper. The dissolved salt will pass through the filter paper while sulphur powder and sand are retained.

- Collect the filtrate (the liquid that passes through) containing dissolved salt.

- Evaporate the water from the filtrate to obtain solid salt.

2. Flotation:

- Add a liquid with a density lower than salt and higher than sand and sulphur, such as kerosene or vegetable oil, to the mixture.

- Sulphur powder and sand will sink, while salt will float on the liquid's surface.

- Carefully pour off the floating salt along with the liquid into another container.

- Allow the liquid to settle, and the salt will precipitate at the bottom.

3. Magnetic Separation:

- If the sand contains magnetic impurities, you can use a magnet to separate it from the non-magnetic sulphur powder and salt.

- Pass a magnet over the mixture, and the magnetic sand particles will be attracted to it.

- Remove the magnet with the attached magnetic sand, leaving behind sulphur powder and salt.

4. Air Classification:

- This method utilizes the different settling velocities of particles in an upward air current.

- Place the mixture in a device called an air classifier.

- An upward stream of air is passed through the mixture, carrying the lighter sulphur powder particles upwards.

- The heavier salt and sand particles settle down, and they can be collected separately.

5. Density Separation (Heavy Liquid Method):

- Use a heavy liquid such as tetrabromoethane or methylene iodide, which has a density greater than salt but less than sand and sulphur.

- Add the heavy liquid to the mixture, and the salt will sink to the bottom while sulphur powder and sand float.

- Carefully pour off the floating sulphur powder and sand.

By applying these methods, you can effectively separate common salt, sulphur powder, and sand from their mixture. The specific choice of method may depend on the availability of resources and the desired level of separation.