Based on its location on the periodic table, which metal is likely to be less reactive than rubidium and more reactive than calcium?

Potassium is above rubidium in Group 1, so it is less reactive; reactivity among alkali metals increases down the group. Potassium is also more reactive than calcium, which is in Group 2, where metals are generally less reactive than alkali metals in the same period. Therefore, the metal is potassium (K).

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