Which of the following groups contains members with similar chemical reactivity? a) sc, y,zr b) li, be, c c) c, n,o d)be, mg, sr

Answer is: D) Be, Mg, Sr.

Beryllium, magnesium and strontium are alkaline earth metals (group 2 of Periodic table of elements).

The elements have very similar properties.

Alkaline earth metals have in common an outer s- electron shell (two electrons). For example, magnesium atom.

Atomic number of magnesium (Mg) is 12, it means that it has 12 protons and 12 electrons.  

Electron configuration of magnesium atom: ₁₂Mg 1s² 2s² 2p⁶ 3s².

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.