Question

which one is the more reactive meatal Cs or Sr?

Answer 1

If your talking about reactivity, Carbon would be more reactive, such as most organic compounds have some sort of carbon in it. It's structure and having 4 valence electrons gives it a great reactivity which the best due to having all half filled orbitals.

Answer 2

Cesium. Both are electropositive metals, but since cesium lies to the left and below strontium, it will be more electropositive (less electronegatiev), so its typical electropositive metal reactivity, in which it loses a valence electron, will be higher than that of strontium.