Gold can be separated from sand by panning or by a sluice-box. In panning, water is mixed with the sand and the resulting slurry is swirled in a shallow, saucer-shaped metal pan. In the sluice-box technique, running water is passed over an agitated sand- gold mixture. What physical property and what technique make this separation possible?

Decantation by means of difference in relative densities.

Explanation:

The specific gravity (relative density) of the gold to the soil/sand is the physical property exploited in panning gold. The particles with lower density would float whilst the heavier gold sinks lower to the bottom of the pan by gravity and is decanted off.

I hope this explanation is easy to comprehend.

pure water does not conduct electricity very well. however, when certain substances are dissolved in water, the solution does conduct electricity. you can make a simple device that shows how well a solution conducts electricity. this device uses a flashlight bulb to indicate how well the solution conducts electricity. the better the solution conducts electricity, the brighter the bulb will glow.

explanation: