Question

Which of the following statements about the elements Mg, Ca, Sr and Ba and their compounds is true?
A.Solubility of hydroxides in water increases with increasing atomic number
B.Thermal stability of the carbonates increases with increasing atomic number
C.All given elements react with water or steam to give hydrogen
D.Metal chlorides are all liquids at room temperature.

Answer 1

Hint: The alkaline earth metals are the elements that correspond to group 2 of the modern periodic table. The elements of this group are beryllium, magnesium, calcium, strontium, barium and radium. Moreover, the elements of this group are quite similar in their physical and chemical properties.

Complete step by step answer:
Basically, the elements whose atoms have their s-subshell filled with their two valence electrons are known as alkaline earth metals. They occupy the second column in the periodic table. These elements are beryllium, magnesium, calcium, strontium, barium and radium. Now, as we move down the column, the nuclear charge increases and a new orbital is added to each alkaline earth metal.
Now, let’s talk about the solubility of hydrides. Basically, the solubility in water is related to the ionic nature and size. We can say that the solubility of hydroxides in water increases with increasing atomic number. Now, carbonates exist as solids and are insoluble in water. The solubility of carbonated decreases from Be to Ba. Moreover, the ionic character and the thermal stability of the carbonates increases from Be to Ba.
Therefore, it is clear that option A and option B are correct. But option C and D are incorrect because all the given elements do not form hydrogen when they react with water and steam. Moreover, all metal chlorides are not liquid at room temperature.

Hence, option A and B are correct.

Note: Alkaline earth metals have low electrode potentials and are obtained by the electrolysis of the fused chlorides. Since, magnesium burns readily in oxygen, the flow of a reducing gas like coal gas is maintained during electrolysis.