Which of the following chlorides is covalent and soluble in ether?

$Ba$,$Ca$,and $Sr$ form halide hydrates. Their formulas are $BaCl_2 \cdot x H_2 O$,$CaCl_2 \cdot y H_2 O$,and $SrCl_2 \cdot z H_2 O$. The values of $x$,$y$,and $z$ respectively are:

The white enamel of our teeth is composed of:

$CaCO_3$ $\xrightarrow[excess \ H_2O]{CO_2 \ in} A$ $\xrightarrow{\Delta} B$
Identify $A$ and $B$.

Why is beryllium amphoteric in nature?

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