Smelting (in a Blast Furnace):
(i) The charge consisting of roasted ore, coke and limestone in the ratio 8:4:1 is smelted in a blast furnace by introducing it through the hopper arrangement at the top.
(ii) There are three important regions in the furnace.

a) The Lower Region (Combustion Zone):
(i) The temperature is at \(1500^{\circ} \mathrm{C}\).
(ii) In this region, coke burns with oxygen to form CO₂ when the charge comes in contact with a hot blast of air.
(iii) It is an exothermic reaction since heat is liberated.
\(\mathbf{C}+\mathbf{O}_{2} \underset{\Delta}{\stackrel{1500^{\circ} \mathrm{C}}{\longrightarrow}} \mathrm{CO}_{2}+ Heat\)
b) The Middle Region (Fusion Zone):
(i) The temperature prevails at \(1000^{\circ} \mathrm{C}\).
(ii) In this region, CO₂ is reduced to CO.
\(\mathrm{CO}_{2}+\mathrm{C} \underset{\Delta}{\stackrel{1000^{\circ} \mathrm{C}}{\longrightarrow}} 2 \mathrm{CO}-\text { Heat }\)
(iii) Limestone decomposes to calcium oxide and CO₂.
\(\mathrm{CaCO}_{3} \underset{\Delta}{\stackrel{1000^{\circ} \mathrm{C}}{\longrightarrow}} \mathrm{CaO}+CO_2-\text { Heat }\)
(iv) These two reactions are endothermic due to absorption of heat.
(v) Calcium oxide combines with silica to form calcium silicate slag.
\(\mathrm{CaO}+\mathrm{SiO}_{2} \longrightarrow \mathrm{CaSiO}_{3}\)
c) The Upper Region (Reduction Zone):
(i) The temperature prevails at \(\mathbf{4 0 0 ^ { \circ } \mathrm { C } \text { . }}\)
(ii) In this region carbon monoxide reduces ferric oxide to form a fairly pure spongy iron.
\(\mathrm{Fe}_{2} \mathrm{O}_{3}+3 \mathrm{CO} \stackrel{400^{\circ} \mathrm{C}}{\longrightarrow} 2 \mathrm{Fe}+3 \mathrm{CO}_{2}\uparrow\)
(iii) The molten iron is collected at the bottom of the furnace after removing the slag.
(iv) The iron thus formed is called pig iron.
(v) It is remelted and cast into different molds.
(vi) This iron is called cast iron.

(i) Copper gets covered with a green layer of basic copper carbonate in the presence of CO₂ and moisture.
(ii) \(2 \mathrm{Cu}+\mathrm{O}_{2}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{CuCO}_{3} \cdot \mathrm{Cu}(\mathrm{OH})_{2}\)
(iii) Copper reacts with con. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) to from copper sulphate and SO₂.
(iv)  \(\mathrm{Cu}+2 \mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{CuSO}_{4}+\mathrm{SO}_{2} \uparrow+2 \mathrm{H}_{2} \mathrm{O}\)
(v)  So, A is-Copper (Cu)
\(\mathrm{B}\ is \ -\mathrm{CuCO}_{3} \cdot \mathrm{Cu}(\mathrm{OH})_{2}\) Basic copper carbonate.
\(\mathrm{C}\ is \ -\mathrm{CuSO}_{4}\) (copper sulphate)
\(\mathrm{D}\ is \ -\mathrm{SO}_{2}\) (Sulphur oxide)

a) Addition of caustic alkali to bauxite ore:
(i) Bauxite ore is finely ground and heated under pressure with a solution of concentrated caustic soda solution at 150^oC to obtain sodium meta aluminate.
(ii) Al₂O₃ + 2 NaOH → 2 NaAlO₂ + H₂O
(iii) On diluting sodium meta aluminate with water, a precipitate of aluminium hydroxide is formed.
(iv) NaAlO₂ + 2 H₂O → Al(OH)₃ + NaOH
(v) The precipitate is filtered, washed, dried and ignited at 1000^oC to get alumina.
(iv) \(2 \mathrm{Al}(\mathrm{OH})_{3} \stackrel{1000^{\circ} \mathrm{C}}{\longrightarrow} \mathrm{Al}_{2} \mathrm{O}_{3}+3 \mathrm{H}_{2} \mathrm{O}\)
b) (i) Electrolyte : Pure alumina + molten cryolite +fluorspar
(ii) Fluorspar is added to lowers the fusion temperature of electrolyte.

(a) Ionic bond.
(b) Electronegativity property.
(c) (i)  Along the period, from left to right in the periodic table, the electronegativity increases, because of the increase in the nuclear charge which in turn attracts the electrons more strongly.
(ii) On moving down a group, the electronegativity of the element decreases because of the increased number of valence shells.

(i) Dilute or concentrated nitric acid renders aluminum passive.
(ii) It does not attack aluminium but it forms oxide film on its surface.

i) Metal A belongs to periods 3 and group 13 is Aluminium.
ii) When steam is passed over red hot aluminium, Aluminium oxide and Hydrogen is produced.
iii) when Aluminium react with strong caustic alkalis forming aluminates

Chemical method or Leaching:
(i) This method is employed when the ore is in a very pure form.
(ii) The ore is treated with a suitable reagent such that the ore is soluble in it but the impurities are not. The impurities are removed by filtration.
(iii) The solution of the ore, ie., the filtrate is treated with a suitable reagent which precipitates the ore.

Magnetic separation method:
(i) Principle: Magnetic properties of the ores form the basis of separation. When either the ore or the gangue is magnetic, this method is employed. E.g. Tin stone SnO₂ The ore of tin.
(ii) Method: The crushed ore is placed over a conveyer belt which rotates around two metal wheels, one of which is magnetic. The magnetic particles are attracted to the magnetic wheel and fall separately apart from the non-magnetic particles.

(i) If the difference in electronegativity between the two elements is 1.7, the bond has 50% ionic character and 50% covalent character.
(ii) If the difference is less than 1.7, the bond is considered to be covalent.
(iii) If the difference is greater than 1.7, the bond is considered to be ionic.

(i) The vertical columns in the periodic table starting from top to bottom are called groups. There are 18 groups in the periodic table.
(ii) As the elements present in a group have identical valence shell electronic configurations, they possess similar chemical properties.
(iii) Vertical columns in the periodic table starting from top to bottom are called groups. There are 18 groups in the periodic table.
(iv) The Lanthanides and Actinides which form part of Group 3 are called inner transition elements.
(v) Except group 0, all the elements present in each groups have same valency. The elements present in a group possess similar chemical properties.
(vi) The physical properties of the elements in a group such as melting point, boiling point and density vary gradually.
(vii) The atoms of the group 0 elements have stable electronic configuration in their valence shells and hence they are unreactive.

(i) The horizontal rows are called periods. There are seven periods in the periodic table.
(ii) First period (Atomic number 1 and 2): This is the shortest period. It contains only two elements (Hydrogen and Helium).
(iii) Second period (Atomic number 3 to 10): This is a short period. It contains eight elements (Lithium to Neon).
(iv) Third period (Atomic number 11 to 18): This is also a short period. It contains eight elements (Sodium to Argon).
(v) Fourth period (Atomic number 19 to 36): This is a long period. It contains eighteen elements (Potassium to Krypton). This includes 8 representative elements and 10 transition eIements.
(vi) Fifth period (Atomic number 37 to 54): This is also a long period. It contains 18 elements (Rubidium to Xenon). This includes 8 representative elements and 10 transition elements.
(vii) Sixth period (Atomic number 55 to 86): This is the longest period. It contains 32 elements (Cesium to Radon). This includes 8 representative elements, 10 transition elements and 14 inner transition elements (Lanthanides).
(viii) Seventh period (Atomic number 87 to 118): Like the sixth period, this period also accommodates 32 elements. Recently 4 elements have been included by IUPAC.