calcium
Iron will react with calcium oxide as iron is more reactive than calcium, therefore calcium (which is the more reactive metal) will displace calcium (the less reactive metal) to form a compound. This is called a displacement reaction.
sodium
Francium is the most reactive metal.
Calcium is a reactive metal whose compounds make up limestone, chalk, cement and teeth. Drinking milk is one way to get this mineral.
Calcium is more reactive but not as Potassium or Sodium because according to the displacement series Calcium comes as third and the last under the reactive elements of the displacement series.
No Calcium is a soft reactive metal. Chlorine is a toxic yellow reactive gas. They react together Ca + Cl2 = CaCl2
reactivity of any element depends on its form.Ca reacts in its Ca+2 form and forms CaCo3 (Calcium carbonate)CaSo4(calcium sulphate) etc.
Not to put too fine a point on it, no. Calcium is a metal, and tasting it would be an exceptionally bad idea since it's a fairly reactive metal and will react with water to form calcium hydroxide.
Zinc nitrate is an amphoteric compound, hence it will react with the reactive metal (calcium). Zn(NO3)2 + Ca --> Ca(NO3)2 + Zn The above is a displacement reaction, where the more reactive calcium displaces the less reactive zinc.
Calcium, period 4 group 2, very reactive
I'm not entirely sure what you mean, but focussing simply on the "least reactive" part: gold is not very reactive, which is why it's called a noble metal.