If both sodium and zinc at room temperature (shiny solver coloured metals) how would you be able to tell?

Sodium is a shiny silver coloured metal at room temp. As is Zinc. If there were both placed in front of you, unlabelled, how would you be able to tell the difference? I know that sodium is an alkali metal, meaning it is highly reactive and Zinc is a transition metal meaning it is less reactive but I am not sure how to tell the difference.