Which element would mostly have chemical properties similar to that of magnesium (mg)?

The elements of same group are placed in same group as they have similar properties. So Calcium is the element which resembles Mangesium.

Calcium and Magnesium both are alkaline earth metals.

They have similar properties as they have similar outer or valence shell electronic configuration

The general electronic configuration of alkaline earht metal is ns2

The electronic configuration of Mg [atomic number 12] and Ca [atomic number 20] are

 and respectively.

it should be all of them because it asks if you included all of those in your answer

explanation:

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.