In a lava lamp, a waxy substance rises and falls repeatedly. What causes the waxy substance to rise? Check all that apply.

Heat from the lamp warms the wax, causing it to expand and become less dense than the surrounding liquid. The less-dense wax is buoyed upward, and its rising is part of the convection current that makes the wax repeatedly rise and fall. Cold or denser wax tends to sink instead.

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