Why are the elements of group-$2$ known as alkaline earth metals?

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ Beryllium has a less negative value of reduction potential compared to the other alkaline earth metals.
Reason $R:$ Beryllium has large hydration energy due to the small size of $Be^{2+}$ but a relatively large value of atomization enthalpy.
In the light of the above statements,choose the most appropriate answer from the options given below.

Which alkaline earth metal sulfate has a hydration enthalpy value greater than its lattice enthalpy value?

As the alkaline earth metals (except $Be$) tend to lose their valence electrons readily,they act as:

Plaster of Paris hardens by:

Observe the following compounds.
$(i)$ $CaCO_3$
$(ii)$ $MgSO_4$
$(iii)$ $BaCl_2$
$(iv)$ $Sr(NO_3)_2$
$(v)$ $MgBr_2$
$(vi)$ $MgCl_2$
The oxoacid salts of group $II$ elements from the above list are