Beryllium magnesium and calcium all are located in the alkaline earth group which of these characteristics do these elements have in common?

They all have similar compounds when combine with oxygen.

Explanation:

Alkaline earth metals are present in group 2 of periodic table. There are six elements in second group. Beryllium, magnesium, calcium, strontium, barium and radium.

All have two valance electrons but in different energy levels.

Electronic configuration of Beryllium:

Be = [He] 2s²

Electronic configuration of magnesium.

Mg = [Ne] 3s²

Electronic configuration of calcium.

Ca = [Ar] 4s²

They are present in group two and have same number of valance electrons (two valance electrons) and show oxidation state +2 by loosing two valance electrons. They also show similar reactivity.

They react with oxygen and form oxide.

2Be   +   O₂   →    2BeO

2Mg  +   O₂   →    2MgO

2Ca +   O₂   →    2CaO

this oxide form hydroxide when react with water,

BeO  + H₂O   →  Be(OH)₂

MgO  + H₂O   →  Mg(OH)₂

CaO  + H₂O   →  Ca(OH)₂

With sulfur,

Mg + S   →  MgS

Ca + S   →  CaS

Ba + S   →  BaS

8 carbon atoms forming single bonds with 18 hydrogen atoms; a triple bond exists between the third and fourth carbon atom from the right

explanation: