The S-block Elements

In alkaline earth metals cationic size increases down the groups, hence thermal stability of carbonates increases down the group. Therefore both assertion and reason are correct and reason is correct explanation of assertion.

Reaction of BeCl₂ and LiAlH₄

2BeCl₂ + LiAlH₄ ->  2BeH₂ + LiCl + AlCl₃

$2B{F}_3+6NaH\to B_2{H}_6+6NaF$

$B_2{H}_6+2\ddot{N}{\left(Me\right)}_3\to 2H_{3}B\leftarrow :N{\left(Me\right)}_3$

Density of metal a very specific and depends upon many factors.

Li -> 0.53 gm/cm³

Na -> 0.97 gm/cm³

K -> 0.86 gm/cm³

Rb ->1.53 gm/cm³

Cs -> 1.90 gm/cm³

Cu is least reactive metal and it lies below hydrogen in reactivity series.

(a) low solubility of LiF in H₂O due to high lattice energy.

(b) $O_2^{-}$  has unpaired e^- thus paramagnetic.

(c) Na in liq NH₃ forms electronated ammonia thus conducting in nature.

(d) $d_K<d_{Na}$ .

Size of hydrated ion $\propto$ $\frac{1}{Ionicmobility}$

Size of hydrated ions $\propto \frac{1}{Ionicsize}$

Size of hydrated ions ; $B{e}^{+2}>M{g}^{+2}>C{a}^{+2}>S{r}^{+2}$

Ionic mobility ; $B{e}^{+2}<M{g}^{+2}<C{a}^{+2}<S{r}^{+2}$

NaOH is obtained by electrolysis of NaCl. Solution of NaCl using Hg cathode

$\begin{array}{l}Cathode:N{a}^{+}+e\underset{}{\overset{Hg}{\to }}Na-Amalgam\\ Anode:2C{l}^{-}\to C{l}_2+2e\\ 2Na-Amalgam+2H_{2}O\to 2NaOH+2Hg+H_2\end{array}$