I think the correct answer from the choices listed above is option D. The element that behaves most like magnesium would be strontium. It behaves most like magnesium<span> because it is in the same family, the alkaline earth metals. Hope this answers the question.</span>
In periodic table, the elements have almost same properties are present in the same group. As Mg and Sr are present in group II-A, so both behave most likely to each other due to having same valence shell electrons as well.
Si and Sn are present in group IV-A which have same behavior but different one from Mg due to different groups.
S is present in group VI-A which show different properties from all others one especially from Mg.
I think the correct answer would be false. The atomic mass of chlorine does not represent the mass of the most common naturally occurring isotope of chlorine. The atomic mass of any compound is the average of the atomic masses of the naturally occurring isotopes of an element. <span />
