Which metal in Period 5 is very reactive and has two valence electrons in each atom?

rubidium (RD)

strontium (SI)

zirconium (Z1)

silver (Ag)

Answer: B. strontium (Sr)

The right answer is A, that is Rubidium (Rb)

Explanation:

Strontium has 2 electrons in the valance shell and is alkaline earth metal but relatively reactive.

Rubidium comes in period 5 and under alkali metals and very reactive towards oxygen and highly reactive than strontium and other option

This element has 2 electrons in its valence subshell (5s) according to Madelung rule.

Madelung rule that if the two orbitals have the same n+l value they fill in increasing order of n.

So the right answer is A, that is Rubidium (Rb)