Soda ash is anhydrous sodium carbonate (Na₂CO₃).

Be and Mg

Alkali metals

BaCl₂ < SrCI₂ < CaCl₂ < MgCl₂

Beryllium does not impart colour to a non-luminous flame

Fused NaOH

NaCl, CaCO₃ and NH₃

Both BaO and BaSO₄ are ionic compounds but the hydration energy of BaO is higher than the lattice energy therefore it is soluble in water.

Lattice energy of BeO is compartively higher than the hydration energy. Therefore, it is almost insoluble in water. Whereas BeSO₄ is ionic in nature and its hydration energy dominates the lattice energy.

2Mg(s) + O₂(g)\(\overset { \triangle }{ \longrightarrow } \)2MgO(s)

Alkali metals dissolve in liquid ammonia and give deep blue solutions which are conducting in nature because ammoniated electrons absorb energy in the visible region of light and impart blue colour.
 M + (x + y)NH₃ \(\longrightarrow \)[M(NH₃)_x]⁺ + \(\underset { Ammoniated\\ \quad electrons }{ (NH_{ 3 })_{ y } } \)

2 Mg + CO_{2 \(\underrightarrow { \Delta } \)}   MgO + \(\frac { 1 }{ 8 } { S }_{ 8 }\)

(i) Alkali and alkaline earth metals are themselves strong reducing agents. Therefore, these metals cannot be obtained by chemical reduction of their oxides and other compounds.
(ii) These metals are highly electropositive in nature.So these cannot be displaced from the aqueous solutions of their salts by other metals.

The Lewis structure of O₂ is  : \(\overset { .. }{ \underset { .. }{ O } } \)  ---  \(\overset { .. }{ O }\):
Oxygen atom carrying no charge has six electrons, so its oxidation number is zero. But oxygen atom carrying -1 charge has 7 electrons, so its oxidation number is -1.
Average oxidation number of each oxygen atom = \(\frac { 1 }{ 2 } \) 
\({ O }_{ 2 }^{ - }\)  = 2x = -1
\(\Longrightarrow \)  x = -\(\frac { 1 }{ 2 } \)

The substance is Na₂O₂. When Na₂O₂ is dissolved in water, it forms NaOH along with H₂O₂. NaOH is a strong base while H₂O₂ is a weak acid.
Na₂O₂ + 2 H₂ O   \(\longrightarrow \)  2 NaOH + H₂O
H₂O₂ turns colour of red litmus paper white due to its bleaching action (which is due to its oxidising character).
H₂O₂  \(\longrightarrow \)  H₂ O + [O]
Na₂ O + H₂ O  \(\longrightarrow \)  2 NaOH
NaOH solution turns colour of red litmus paper into blue due to its stronger alkaline character.