The three similarities are hydrogen is produces, metal floats and move around the water, and metal disappeared. The difference is potassium is more reactive than lithium.
When metal reacts with water, hydrogen and metal hydroxide is produced.
Potassium is more reactive than lithium.
Alkali metals are also reactive with water.
The metal self ignites.
Thus, the three similarities are hydrogen is produces, metal floats and move around the water, and metal disappeared. The difference is potassium is more reactive than lithium.
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