2.30     describe how reactions with water and dilute acids can be used to deduce the following order of reactivity: potassium, sodium, lithium, calcium, magnesium, zinc, iron, and copper

Metal	Air	Water	Dilute acid (HCl)
potassium	burns easily	violent with cold water	violent
sodium	burns easily	very fast with cold water	violent
lithium	burns easily	fast with cold water	very fast
calcium	burns easily	quite fast with cold water	very fast
magnesium	burns easily	steam needed	fast
zinc	slow, heat needed	steam needed	reacts steadily
iron	slow, heat needed	steam needed	reacts slowly
copper	slow, heat needed	no reaction	no reaction