Which element has an electron configuration of [kr]5s2?

Strontium

Explanation:

Strontium is a silvery-white, soft metal, good conductor of electricity. When exposed to air, it oxidizes quickly and therefore must be stored in kerosene. Upon combustion in the air, it produces a bright light and forms the oxide and the nitride of strontium. It reacts with water and from this process is formed the strontium hydroxide and released the molecular hydrogen.

It is an abundant element in nature: it is present, in the form of strontium compounds, in magmatic rocks. It is not found in its metallic form, but especially in the form of strontium sulphate.

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume