Chlorides of which metal are soluble in organic solvents:

Portland cement contains '$X$' to enhance the setting time. What is '$X$'?

Statement $A$: Helium and Beryllium have the same outer electronic configuration of the type $ns^2$.
Reason $R$: Both are chemically inert.

The white enamel of our teeth is composed of:

What are $X$,$Y$ and $Z$ in the following reactions?
$CaCO_3 \stackrel{\Delta}{\rightleftharpoons} CO_2 + X$
$X + H_2O \longrightarrow Y$
$Y + Cl_2 \longrightarrow Z$

Alkaline earth metals (except $Be$) can easily lose their valence electrons,so how do they behave?