Which of the following ions forms a hydroxide that is readily soluble in water?

Select the correct statement from the following.

Assertion : The ionic radii of the alkaline earth metals are smaller than those of alkali metals in the same period.
Reason : Alkali metals have higher nuclear charge than that of the alkaline earth metals.

Which of the following substances is unlikely to contain $CaCO_3$?

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.

Compounds of alkaline earth metals are less soluble in water than the corresponding alkali metal compounds due to