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]⁺ + \(\underset { Ammoniated\\ \quad electrons }{ (NH_{ 3 })_{ y } } \)

NH₄HCO₃ + NaCl \( \rightarrow\) NH₄Cl + NaHCO₃
Thus ,C  is sodium bicarbonate

Sodiun : NaCl
Pottassium : KCl

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.

Nitrates of both group 1 and group 2 elements are soluble in water because hydration energy is more than the lattice energy.
Nitrates of both group 1 and group 2 elements are thermally unstable but they decompose differently except LiNO₃ e.g.
2NaNO₃ \(\overset { heat }{ \longrightarrow } \) 2NaNO2 + O₂
2KNO₃ \(\overset { \triangle }{ \longrightarrow } \) 2KNO₂ + O₂
4LiNO₃ \(\overset { \triangle }{ \longrightarrow } \) 2Li₂O + 4NO₂ + O₂
2Mg(NO3)₂  \(\overset { \triangle }{ \longrightarrow } \) 2MgO + 4NO₂ + O₂

(i) Atomic size goes on increasing down the group
(ii) Ionisation energy goes on decreasing down the group.
(iii) They are harder than alkali metals
(iv) They are less electropositive than alkali metals
(v) Electropositive character increases on going down the group.

Slaked lime is calcium hydroxide, Ca(OH)₂.
\(CaO+{ H }_{ 2 }O\longrightarrow Ca(OH{ ) }_{ 2 }\)

Because aluminium reacts with water and oxygen (dissolved in ) to form a thin layer of toxic aluminium oxide on the surface of utensils.
2Al(s) + O₂(g) + H₂O(l)\(\rightarrow\)Al₂O₃(s) + H₂(g)

Sodium ions:
(i) Na⁺ ions participate in the transmission of nerve signals, in regulating the flow of water across cell membranes.
(ii) In the transport of sugars and amino acids into cell.
Potassium ions:
(i) They activate many enzymes.
(ii) Participate in the oxidation of glucose to produce ATP.
Magnesium ions:
(i) All enzymes that utilise ATP in phosphate transfer require magnesium as a cofactor.
(ii) Mg is the main pigment for the absorption of light in plants.
Calcium:
(i) Ca²⁺ ions are present in bones.
(ii) plays important roles in neuromuscular function

Sodium carbonate It is obtained by Solvay ammonia process 
when CO₂ is passed through a concentrated solution of brine (aqeuous solution of NaCl) saturated with ammonia, NaHCO₃ gets precipitated.NaHCO₃ on Subsequent hetaing gives Na2CO₃.
NaCl + NH₃ + H₂O\(\xrightarrow{\Delta}\) NaHCO₃ + NH₄Cl
2NaHCO₃\(\xrightarrow{\Delta}\)  Na₂CO₃ + CO₂ + H₂O

Vitamin D

CuCl is more covalent because Cu⁺ ion have pseudo noble gas confgration , which have more polarising power than NA⁺ ion

This is because magnesium react with sulphur to from MgO(magnesium oxide) and s (sulphur). TYhis reaction is exothermic and keeps the piece of magnesium burning 2Mg + SO₂ \(\rightarrow\) 2Mgo + S