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The more negative or less positive is the electrode potential, more is the reducing strength of the species. Since the electrode potentials increases in the order: 

Li(-3.04V) < Na(-2.7V) < I^-(0.53 V) < Ag(+0.79V) < Cl^- (+1.36V), 

therefore, the reducing strength decreases in the order 

Li > Na > I^- > Ag > Cl^-

NaCl contains impurities of some other salts like Na₂SO₄, MgCl₂ ets. Which absorb water vapour from air, thus making it wet.

KOH is the strongest base.

It is because of the fact that both NaOH and KOH are highly deliquescent. These compounds absorb moisture from air and changes into solution.

d. BeO is acidic while MgO is amphoteric.

d. BeCl₂ + H₂

2 KO₂+2 H₂O → 2KOH + H₂O₂+O₂

2KO₂ (Pottasium sup eroxide) + 2H₂O → 2KOH + O₂ + H₂O₂

Limestone and clay are raw materials used in manufacture of cement. It is prepared by heating powdery mixture of limestone and clay in dry process. In wet process, fine – powdered mixture is converted into slurry by adding water and then it is heated at a temperature 1500°C to 1600°C, the product formed is called clinkers. It is cooled down and mixed with gypsum (CaSO₄, 2H₂O) and then it is powdered.

Ba(OH)₂ > Sr(OH)₂ > Ca(OH)₂ > Mg(OH)₂ > Be(OH)₂ 

Solubility of hydroxides goes on increasing down the group because hydration energy dominates over lattice energy. 

BaSO₄ < SrSO₄ < CaSO₄ < MgSO₄ < BeSO₄

Li₂CO₃ is thermally unstable because it is covalent. It decomposes to form Li₂O and CO₂

Li₂CO₃ → Li₂O + CO₂

BaCO₃ is thermally most stable due to greater ionic character and high lattice energy whereas BaCO₃ is thermally least stable because it is covalent and has less lattice energy.

This is due to strong polarizing effect of small Be²⁺ on the larger and more polarizable CO₃^2- anions.

The greater hydration enthalpies of Be²⁺ and Mg²⁺ ions overcome the lattice enthalpy factor and therefore their sulphates are soluble in water.

The valence electrons get excited to a higher energy level when an alkaline earth metal is heated.It radiates energy which belongs to the visible region when this excited electron comes back to its energy level which is low. The colour is observed here. The electrons are strongly bound in the beryllium and magnesium. The energy required to excite these electrons is very high. When the electron reverts back to its original position, the energy released does not fall in the visible region. Hence, no colour is seen in the flame.

Beryllium does not impart colour to a non-luminous flame.

Beryllium does not impart colour to a non – luminous flame.

Due to high reactivity of alkali metals with air and water. 

(i) Small size ∝ Hydrations energy ∝ \(\frac{1}{ionic\,mobility}\)

(ii) Lithium on account of its small size, shows anomalous behavior.

(iii) BaO is soluble but BaSO₄ is insoluble on account of higher lattice energy of BaSO₄ than its hydration energy.

(i) The alkaline earth metals can not be obtained by reduction of their formation because the enthalpies of formation of these oxides are quite high and consequently they are very stable to heat.

(ii) The elements of group 2 are known as alkaline earth metals because their oxides and hydroxides are alkaline in nature and these metal oxides are found in the earth’s crust.

(i) Beryllium and magnesium atoms are smaller in size and their electron are strongly bound to the nucleus. They need large amount of energy levels which is not available in the Bunsen flame. So they do not impart colour to the flame.

(ii) Due to low ionization energies, alkali metals, specially potassium and caseium, eject electrons when exposed to light, therefore, photoelectric cells.

(iii) As we move down the alkali metal group, the electropositive character increases. This causes an increase in the stability of alkali carbonates. However, lithium carbonate is not so stable to heat. This is because lithium carbonate is covalent. Lithium a large carbonate ion, leading to the formation of more stable lithium oxide.

Li₂CO₃ \(\overset{\Delta}{\rightarrow}\) Li₂O + CO₂

Therefore, lithium carbonate decomposes at a low temperature while a stable sodium carbonate decomposes at a high temperature.

Isomorphous salts are those which have same crystalline structure, e.g., MgSO₄, 7H₂O and ZnSO₄,7H₂O are isomorphous.

a. Mg²⁺, K⁺  metal ion are present in carnalite.

This is because the heat from the flame excites the outer orbital electron to a higher energy level.

oxides of lithium and magnesium are less soluble in H₂O. also the hydroxides of both decompose at high temperature.

2LiOH→Li₂O+H₂O 

Mg(OH)₂→MgO+H₂O

(ii) Nitrides is formed from both the lithium and magnesium when they react with N_2.

6Li+N₂→2Li₃N 

3Mg+N₂→Mg₃N₂

(iii)Neither Li nor Mg form superoxides or peroxides.

Due to (diagonal relationship)

(i) Similarity in atomic size

(ii) Similar charge to size ratio.

Beryllium hydroxide is amphoteric.

Alkali metals give characteristics flame coloration because the heat from the flame excites the outermost orbital electron to a higher energy level. When the excited electron comes back to the ground state, there is emission of radiation invisible region.

Quick lime is calcium oxide. It is prepared by heating limestone.

When quick lime is heated with silica, it form calcium silicate.
CaO + SiO₂ ➝ CaSiO₃

Be shows similarities with Al because it shows diagonal relationship with Al.

Baking soda is sodium bicarbonate (NaHCO₃) while baking powder is a mixture of sodium bi-carbonate (NaHCO₃) and potassium hydrogen tartarate.

Baking soda is sodium bicarbonate (NaHCO₃). Which baking powder is a mixture of sodium bicarbonate (NaHCO₃) and potassium hydrogen tartar ate.

(Plaster of Paris) Calcium Sulphate CaSO₄· H₂O (Baking Soda), NaHCO_3.

Be and Mg do not give characteristics colour to the flame because the electrons in Be and Mg are too strongly bound to get excited by flame.

[Noble gas] ns^1-2 

Thermal stability of carbonates of alkaline earth metal ∞ size of cation.

\(\therefore\) Decreasing order of thermal stability is-

BaCO₃ > SrCO₃ > CaCO₃ > MgCO₃ > BeCO₃

(i) When heated with excess of air, lithium forms normal oxide, Li₂O sodium forms peroxide, Na₂O₂ , whereas potassium, rubidium and caesium form superoxide’s having general formula MO₂.

4Li + O₂ → 2Li₂O

2Na + O₂ → Na₂O₂

K + O₂ → KO₂

(ii) Baking soda: It is prepared commercially by dissolving soda ash in water and treating with carbon dioxide.

Na₂CO₃ + CO₂ + H₂O → 2NaHCO₃

(iii) Alkali metals are more reducing than alkaline earth metals because of low ionisation energy.

(iv) Alkaline earth metals impart colour to flame but be and Mg do not, because they do not have unpaired electrons for excitation.

(v) Alkali metals ns¹

Alkaline earth metals ns²

BaCO₃ > SrCO₃ > CaCO₃ > MgCO₃ > BeCO₃

Alkali metals form unipositive ions which have stable configuration of the nearest inert gas. Alkali metal salts are diamagnetic and colorless because they do not have impaired electrons.

Potassium, rubidium and caesium form super oxides when heated in excess of air.

Thermal stability of alkaline earth metal carbonates increases down the group due to increase in ionic character and therefore, increase in lattice energy

Basic strength of alkaline earth metal hydroxides increases down the group because ionization energy of metal decreases and electropositive character increases down the group.

Li is the smallest atom in 1st group alkali metal. So Li⁺ ion is the smallest among the alkali metal ions. The polarising power of ion increases with the decrease in size of the ion. So the polarising power of Li+ is much greater than that of any other ion of the group and is therefore capable of polarising water molecules to entrap them as water of crystallization showing high value of enthalpy of hydration.

The hydration enthalpies of alkali metal ions decrease with increase in ionic sizes. Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺ Li⁺ has maximum degree of hydration and for this reason lithium salts are mostly hydrated.

(i) Among alkaline earth metal hydroxides, the anion being common the cationic radius will influence the lattice enthalpy.

Since lattice enthalpy decreases much more than the hydration enthalpy with increasing ionic size, the solubility of alkaline earth metal hydroxides in water increases down the group.

(ii) The size of anions being much larger compared to cations the lattice enthalpy will remain almost constant with in a particular group.

Since the hydration enthalpies decrease down the group, so, solubility of alkaline earth metal carbonates and sulphates in water decrease down the group.

(i) Lithium is the smallest in size among all the elements of the alkali metals groups. Hence, lithium ion can polarize water molecules more easily than other alkali metals. As a result, water molecules get attached to lithium salts as water of commonly hydrated. As the ionic size increases, their polarizing power decreases. So, other alkali metal ions are usually anhydrous.

(ii) (a) Lithium is least reactive but the strongest reducing agent among all the alkali metals.

(b) Lithium nitrates decompose to give the corresponding nitrite.

4LiNO₃ → 2Li₂O + 4NO₂ + O₂

2NaNO₃ → 2NaNO₂ + O₂

CaSO₄ is called dead burnt plaster. It is obtained by heating gypsum at high , temperature.