Explanation: The reason that the raisins rise and sink is that the soda has lots of carbon dioxide gas in it, and the gas tends to form bubbles and cling to flat surfaces. When enough bubbles collect, the raisin is raised to the top. The bubbles then escape out the top of the glass and the raisin sinks again. Note: you can also do this experiment using baking soda and vinegar to produce the CO2 gas.
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