{"id":2023,"date":"2023-02-03T01:14:36","date_gmt":"2023-02-02T19:44:36","guid":{"rendered":"https:\/\/apboardsolutions.com\/?p=2023"},"modified":"2023-03-29T16:56:59","modified_gmt":"2023-03-29T11:26:59","slug":"ap-ssc-10th-class-chemistry-solutions-chapter-13","status":"publish","type":"post","link":"https:\/\/apboardsolutions.com\/ap-ssc-10th-class-chemistry-solutions-chapter-13\/","title":{"rendered":"AP SSC 10th Class Chemistry Solutions Chapter 13 Principles of Metallurgy"},"content":{"rendered":"

AP State Board Syllabus\u00a0AP SSC 10th Class Chemistry Solutions<\/a> Chapter 13 Principles of Metallurgy Textbook Questions and Answers.<\/p>\n

AP State Syllabus SSC 10th Class Chemistry Solutions 13th Lesson Principles of Metallurgy<\/h2>\n

10th Class Chemistry 13th Lesson Principles of Metallurgy Textbook Questions and Answers<\/h3>\n

Review of Your Previous Knowledge<\/span><\/p>\n

Question 1.
\nCan you mention some articles that are made up of metals?
\nAnswer:
\nJewellery, conducting wires, utensils, etc.<\/p>\n

Question 2.
\nDo metals exist in nature in the form same as that we use in our daily life?
\nAnswer:
\nNo, they exist as ores and minerals.<\/p>\n

\"AP<\/p>\n

Question 3.
\nHave you ever heard the words like ore, mineral and metallurgy?
\nAnswer:
\nYes, these words are related to extraction of metals.<\/p>\n

Question 4.
\nDo you know how these metals are obtained?
\nAnswer:
\nThese metals are generally extracted from their ores.<\/p>\n

Improve Your Learning<\/span><\/p>\n

Question 1.
\nList three metals that are found in nature as oxide ores.
\nAnswer:
\nThe three metals that are found in nature as oxide ores are<\/p>\n

    \n
  1. Bauxite (Al2<\/sub>O3<\/sub> 2H2<\/sub>O)<\/li>\n
  2. Haematite (Fe2<\/sub>O3<\/sub>)<\/li>\n
  3. Zincite (ZnO).<\/li>\n<\/ol>\n

    Question 2.
    \nList three metals that are found in nature in uncombined form.
    \nAnswer:
    \nThe three metals that are found in nature in uncombined form are<\/p>\n

      \n
    1. Gold<\/li>\n
    2. Silver<\/li>\n
    3. Platinum.<\/li>\n<\/ol>\n

      Question 3.
      \nWrite a note on dressing of ore in metallurgy.
      \n(OR)
      \nWhat is concentration of Ore? List various physical methods that are used to enrich the ore.
      \nAnswer:<\/p>\n

        \n
      • Ores that are mined from the earth are usually contaminated with large amount of impurities such as soil and sand, etc.<\/li>\n
      • Concentration or dressing means, simply getting rid of as much of the unwanted rocky material as possible from the ore. The impurities like sand and clay are called gangue.<\/li>\n<\/ul>\n

        The physical methods adopted in dressing of the ore or enriching the ore depends upon the difference between physical properties of ore and gangue.<\/p>\n

        Methods of dressing or concentration of the ore:
        \n1. Hand picking :
        \nIf the ore particles and the impurities are different in one of the properties like colour, size, etc. using that property, the ore particles are handpicked separating them from other impurities.<\/p>\n

        2. Washing:<\/p>\n

          \n
        • We use washing method with water to separate dust from rice, dal and vegetable fruits, etc.<\/li>\n
        • Ore particles are crushed and kept on a slopy surface. They are washed with controlled flow of water. Less densive impurities are carried away by water flow, leaving the more densive ore particles behind.<\/li>\n<\/ul>\n

          3. Froth flotation:
          \nThis method is mainly useful for sulphide ores. The ore with impurities is finely powdered and kept in water taken in a flotation cell. Air under pressure is blown to produce froth in water. Froth so produced, takes the ore particles to the surface whereas impurities settle at the bottom. Froth is separated and washed to get ore particles.<\/p>\n

          4. Magnetic separation:
          \nIf the ore or impurity, one of them is magnetic substance and the other is non-magnetic substance, they are separated using electromagnets.<\/p>\n

          \"AP<\/p>\n

          Question 4.
          \nWhat is an ore? On what basis a mineral is chosen as an ore?
          \nAnswer:
          \nOre :
          \nA mineral from which a metal can be extracted economically and conveniently is called ore.
          \nA mineral is chosen as an ore if the mineral is economical and profitable to extract.<\/p>\n

          Example:
          \nAluminium is the common metal in the Earth\u2019s crust in all sorts of minerals. It is economically feasible and profitable to extract from bauxite which contains 50-70% of aluminium oxide.<\/p>\n

          Question 5.
          \nWrite the names of any two ores of iron.
          \nAnswer:
          \nThe names of two ores of iron :<\/p>\n

            \n
          1. Haematite (Fe2<\/sub>O3)<\/li>\n
          2. Magnetite (Fe3<\/sub>O4<\/sub>).<\/li>\n<\/ol>\n

            Question 6.
            \nHow do metals occur in nature ? Give examples to any two types of minerals.
            \nAnswer:<\/p>\n

              \n
            • The earth\u2019s crust is the major source of metals.<\/li>\n
            • Sea water also contains some soluble salts such as sodium chloride and magnesium chloride etc.<\/li>\n
            • Some metals like gold (Au), silver (Ag) and copper (Cu) are available in nature in free state as they are least reactive.<\/li>\n
            • Other metals are found in nature in the combined form due to their more reactivity.<\/li>\n
            • The elements or compounds of the metals which occur in nature in the earth’s crust are called minerals.<\/li>\n<\/ul>\n

              Examples :
              \nMinerals in oxide form :
              \nBauxite, Zincite, Magnetite, etc.<\/p>\n

              Minerals in sulphide form :
              \nCopper iron pyretes, Galena, etc.<\/p>\n

              \"AP<\/p>\n

              Question 7.
              \nWrite short notes on froth flotation process.
              \n(OR)
              \nWhich method is useful for concentration of sulphide ore? Explain the method.
              \nAnswer:
              \nFroth Floatation process :<\/p>\n

                \n
              • This method is mainly useful for sulphide ores which have no wetting property whereas impurities get wetted.<\/li>\n
              • The ore with impurities is finely powdered and kept in water taken in a floatation cell.<\/li>\n<\/ul>\n

                \"AP
                \nFroth floatation process for the concentration of sulphide ores<\/p>\n

                  \n
                • Air under pressure is blown to produce froth in water.<\/li>\n
                • Froth so produced takes the ore particles to the surface whereas impurities settle at the bottom.<\/li>\n
                • Froth is separated and washed to get ore particles.<\/li>\n<\/ul>\n

                  Question 8.
                  \nWhen do we use magnetic separation method for concentration of an ore? Explain with an example.
                  \n(OR)
                  \nWrite the name of the method we use to separate the ore or impurity in which one of them is magnetic substance. Draw a neat diagram indicating the method.
                  \nAnswer:
                  \nIf the ore or impurity, one of them is magnetic substance and the other non-magnetic substance they are separated using electromagnets.
                  \nEx :
                  \nIron from iron ore (Fe3<\/sub>O4<\/sub>) is separated from its impurity by passing through a magnetic field. The field attracts magnetic ore (Iron) and repels the non-magnetic impurities.
                  \n\"AP<\/p>\n

                  Question 9.
                  \nWrite short notes on each of the following :
                  \ni) Roasting
                  \nii) Calcination
                  \niii) Smelting
                  \nAnswer:
                  \ni) Roasting :
                  \nRoasting is a pyrochemical process in which the ore is heated in the presence of oxygen or air, below its melting point. Generally, reverberatory furnace is used for roasting.
                  \nEx:
                  \nZinc blende on heating with oxygen in reverberatory furnace forms zinc oxide as solid and liberating sulphur dioxide as gas.
                  \n2Zns(s)<\/sub> + 3O2(g)<\/sub> \u2192 2ZnO(s)<\/sub> + 2SO2(g)<\/sub><\/p>\n

                  ii) Calcination :
                  \nCalcination is a pyrochemical process in which the ore is heated in the absence of air. The ore gets generally decomposed in this process.
                  \nEx: MgCO3(s)<\/sub> \u2192 MgO(s)<\/sub> + CO2(g)<\/sub><\/p>\n

                  iii)Smelting:
                  \nSmelting is a pyrochemical process, in which the ore is mixed with flux and fuel, then is strongly heated.<\/p>\n

                  \"AP<\/p>\n

                  Question 10.
                  \nWhat Is the difference between roasting and calcination? Give one example for each.
                  \n(OR)
                  \nRoasting and Calcination are the methods to extract crude metals from ores. What is the difference between Roasting and Calcination?
                  \nAnswer:<\/p>\n\n\n\n\n\n\n\n\n
                  Roasting<\/td>\nCalcination<\/td>\n<\/tr>\n
                  1. Roasting is a pyrochemical process in which the ore is heated in the presence of air below its melting point.<\/td>\n1. Calcination is a pyrochemical process in which the ore is heated in the absence of air.<\/td>\n<\/tr>\n
                  2. It is an oxidation reaction.<\/td>\n2. It is a decomposition reaction.<\/td>\n<\/tr>\n
                  3. It requires oxygen.<\/td>\n3. It doesn’t require oxygen.<\/td>\n<\/tr>\n
                  4. It is suitable to sulphide ores.<\/td>\n4. It is suitable to carbonate ores.<\/td>\n<\/tr>\n
                  5. Ex : 2ZnS + 3O2<\/sub> \u2192 2ZnO + 2SO2<\/sub><\/td>\n5. Ex : CaCO3<\/sub>\u00a0\u2192 CaO + CO2<\/sub><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                  Question 11.
                  \nDefine the terms:
                  \ni) gangue
                  \nii) slag.
                  \nAnswer:
                  \ni) Gangue:
                  \nThe impurity present in the ore is called gangue.
                  \n(or)
                  \nUnwanted impurity associated with ore.<\/p>\n

                  ii) Slag:
                  \nThe impurities found from molten metal during poling process of refining are called slag.<\/p>\n

                  Question 12.
                  \nMagnesium is an active metal if it occurs as a chloride in nature, which method of reduction is suitable for its extraction?
                  \nAnswer:<\/p>\n

                    \n
                  • The method of reduction which is useful for chloride of magnesium which is active is electrolytic reduction.<\/li>\n
                  • Fused MgCl2<\/sub> is electrolysed with steel cathode (-) and graphite anode (+). The metal (Mg) will be deposited at cathode and chlorine gas liberates at the anode.
                    \nAt cathode : Mg2+<\/sup> + 2 e–<\/sup> \u2192 Mg
                    \nAt anode : 2 Cl–<\/sup> \u2192 Cl2<\/sub> + 2e–<\/sup><\/li>\n<\/ul>\n

                    \"AP<\/p>\n

                    Question 13.
                    \nMention two methods which produce very pure metals.
                    \nAnswer:
                    \nMethods which produce very pure metals are :<\/p>\n

                      \n
                    1. Electrolytic Reduction<\/li>\n
                    2. Smelting.<\/li>\n<\/ol>\n

                      (OR)<\/p>\n

                        \n
                      1. Distillation<\/li>\n
                      2. Poling.<\/li>\n<\/ol>\n

                        Question 14.
                        \nWhich method do you suggest for extraction of high reactivity metals? Why?
                        \nAnswer:
                        \n1.The only method which is suitable for extraction of high reactivity metals is electrolysis of their fused compounds.<\/p>\n

                        2. Other methods are not suitable due to following reasons :
                        \na) Simple reduction methods like heating with C, CO, etc. to reduce the ores of these metals are not suitable because the temperature required for the reduction is too high and more expensive.<\/p>\n

                        b) Electrolysis of their aqueous solutions are also not preferable because water in the solution would be discharged at the cathode in preference to the metal ions.<\/p>\n

                        Question 15.
                        \nSuggest an experiment to prove that the presence of air and water is essential for corrosion. Explain the procedure.
                        \n(OR)
                        \nWrite the experimental procedure to prove that water and air are essential for rusting of iron articles.
                        \n(OR)
                        \nHow can you prove that the presence of air and humid are essential for corrosion?
                        \n(OR)
                        \nExplain in brief, an experiment to prove that the presence of air and water are essential for corrosion.
                        \nWrite the precautions to be taken in the experiment to show air and water are essential for rusting iron articles and also write the experimental procedure.
                        \nAnswer:
                        \nAim :
                        \nTo prove that the presence of air and water is essential for corrosion or for rusting of iron articles.<\/p>\n

                        Apparatus :
                        \n3 boiled test tubes, 3 corks, boiled distilled water, anhydrous calcium chloride, clean iron nails.<\/p>\n

                        \"AP<\/p>\n

                        Procedure :<\/p>\n

                          \n
                        • Take three test tubes and place clean iron nails in each of them.<\/li>\n
                        • Label these test tubes A, B and C. Pour some water in test tube A and cork it.<\/li>\n
                        • Pour boiled distilled water in test tube B, add about 1 ml of oil and cork it. The oil will float on water and prevent the air from dissolving in the water.<\/li>\n
                        • Put some anhydrous calcium chloride in test tube C and cork it. Anhydrous calcium chloride will absorb the moisture.<\/li>\n
                        • Leave these test tubes for a few days and then observe.<\/li>\n
                        • We will observe that iron nails rust in test tube A, but they do not rust in test tubes B and C.<\/li>\n<\/ul>\n

                          Observation :<\/p>\n

                            \n
                          • In test tube A, the nails are exposed to air and water. Hence, the nails rusted.<\/li>\n
                          • In test tube B, the nails are exposed only to water, but not to air, because the oil float on water and prevent the air from dissolving in the water. Hence, the nails are not rusted.<\/li>\n
                          • In test tube C, the nails are exposed to dry air, because anhydrous calcium chloride will absorb the moisture, if any, from the air. Hence, the nails are not rusted.<\/li>\n<\/ul>\n

                            Conclusion :
                            \nFrom the above experiment we can prove that air and water are essential for corrosion.<\/p>\n

                            \"AP<\/p>\n

                            Question 16.
                            \nCollect information about extraction of metals of low reactivity silver, platinum and gold and prepare a report.
                            \n(OR)
                            \nPrepare a report with the collected information about extraction of metals of low reactivity silver, platinum and gold.
                            \nAnswer:
                            \nExtraction of Silver:<\/p>\n

                              \n
                            1. Silver can be extracted from Ag2S by using displacement from aqueous solution.<\/li>\n
                            2. Ag2<\/sub>S is dissolved in KCN solution to get dicyanoargentate (I) ions.<\/li>\n
                            3. From these ions Ag is precipitated by treating with Zinc dust powder.
                              \nAg2<\/sub>S + 4 CN–<\/sup> \u2192 2 [Ag(CN)2<\/sub>]–<\/sup> + S2-<\/sup>
                              \n2[Ag(CN)2<\/sub>]–<\/sup>(aq)<\/sub> + Zn(s)<\/sub> \u2192 [Zn(CN)4<\/sub>]2-<\/sup>(aq)<\/sub> + 2Ag(s)<\/sub><\/li>\n<\/ol>\n

                              Extraction of Gold :<\/p>\n

                                \n
                              1. Gold is extracted from gold ore like electrum. Impurities are separated from the gold by treating gold ore with a weak cyanide solution.<\/li>\n
                              2. Zinc is added and a chemical reaction takes place which separates the gold from ore.<\/li>\n
                              3. Pure gold is removed from the solution with a filter press.<\/li>\n<\/ol>\n

                                Extraction of Platinum:<\/p>\n

                                  \n
                                1. The extraction of platinum from ore is a complex process and includes milling the ore, a froth flotation process, and smelting at high temperatures.<\/li>\n
                                2. This removes the base metals, notably iron and sulphur and concentrate platinum.<\/li>\n<\/ol>\n

                                  Question 17.
                                  \nDraw the diagram showing
                                  \ni) Froth flotation
                                  \nii) Magnetic separation.
                                  \n(OR)
                                  \nDraw a neat diagram and label the parts that shows froth floatation process for the concentration of sulphide ore.
                                  \nAnswer:
                                  \ni)
                                  \n\"AP
                                  \nii)
                                  \n\"AP<\/p>\n

                                  Question 18.
                                  \nDraw a neat diagram of reverberatory furnace and label it neatly.
                                  \n(OR)
                                  \nDraw a neat labelled diagram of a reverberatory furnace.
                                  \nAnswer:
                                  \n\"AP<\/p>\n

                                  Question 19.
                                  \nWhat is activity series? How does it help in extraction of metals?
                                  \nAnswer:
                                  \nActivity Series :
                                  \nWe can arrange metals in descending order of their reactivity. This series of writing metals is called activity series.<\/p>\n

                                  Uses of activity series the extraction of metals :<\/p>\n

                                    \n
                                  • Activity series is extremely useful in extraction of metals because we can judge the nature of metal and how it exists.<\/li>\n
                                  • High reactive metals like K, Na, Ca, Mg and Al are so reactive that they are never found in nature in free state.<\/li>\n
                                  • The moderate reactive metals like Zn, Fe, Pb, etc. are found in the earth’s crust mainly as oxides, sulphides and carbonates.<\/li>\n
                                  • The least reactive metals like Au, Ag, Pt are found even in free state in nature.<\/li>\n<\/ul>\n

                                    Question 20.
                                    \nWhat is thermite process? Mention its applications in daily life.
                                    \nAnswer:
                                    \nThermite Process :<\/p>\n

                                      \n
                                    • Thermite process is the chemical reaction which takes place between metal oxides and aluminium.<\/li>\n
                                    • When highly reactive metals such as sodium, calcium, aluminium, etc. are used as reducing agents, they displace metals of lower reactivity from the compound.<\/li>\n
                                    • This reaction is highly exothermic. The amount of heat evolved is so high that the metals can he directly converted into molten state.<\/li>\n<\/ul>\n

                                      Applications in daily life :<\/p>\n

                                        \n
                                      • The reaction if Iron (III) oxide (Fe203) with aluminium is used to join railing of railway tracks or cracked machine parts.
                                        \n2 Al + Fe2<\/sub>O3<\/sub> \u2192 Al2<\/sub>O3<\/sub> + 2 Fe + Heat.<\/li>\n
                                      • And also used for joining of cracked metal utensils in the house.<\/li>\n<\/ul>\n

                                        \"AP<\/p>\n

                                        Question 21.
                                        \nWhere do we use hand picking and washing methods in our daily life ? Give examples.
                                        \nHow do you correlate these examples with enrichment of ore?
                                        \nAnswer:
                                        \nDaily life examples for hand picking:<\/p>\n

                                          \n
                                        • Separating mud particles from rice is an example for hand picking because the colour and size of these two are different.<\/li>\n
                                        • Similarly, the ore particles and the impurities are different in one of the properties like colour, size, etc. are separated by hand picking.<\/li>\n<\/ul>\n

                                          Daily life examples for washing :<\/p>\n

                                            \n
                                          • We can clean some vegetables like potatoes by controlled flow of water. Less densive impurities are carried away by the flow leaving the more densive potatoes.<\/li>\n
                                          • Similarly, ores are washed with controlled flow of water. Less densive impurities i are carried away by water flow, leaving the more densive ore particles behind.<\/li>\n<\/ul>\n

                                            Fill In The Blanks<\/span><\/p>\n

                                            1. The method is suitable to enrich the sulphide ores.
                                            \n2. Arranging metals in the decreasing order of their reactivity is called
                                            \n3. The method suitable for purification of low boiling metals.
                                            \n4. Corrosion of iron occurs in the presence of and
                                            \n5. The chemical process in which the ore is heated in the absence of air is called
                                            \nAnswer:<\/p>\n

                                              \n
                                            1. Froth flotation<\/li>\n
                                            2. activity series<\/li>\n
                                            3. distillation<\/li>\n
                                            4. air, water<\/li>\n
                                            5. calcination<\/li>\n<\/ol>\n

                                              Multiple Choice Questions<\/span><\/p>\n

                                              1. The impurity present in the ore is called ………………….
                                              \nA) Gangue
                                              \nB) Flux
                                              \nC) Slag
                                              \nD) Mineral
                                              \nAnswer:
                                              \nA) Gangue<\/p>\n

                                              2. Which of the following is a carbonate ore?
                                              \nA) Magnesite
                                              \nB) Bauxite
                                              \nC) Gypsum
                                              \nD) Galena
                                              \nAnswer:
                                              \nA) Magnesite<\/p>\n

                                              \"AP<\/p>\n

                                              3. Which of the following is the correct formula of Gypsum?
                                              \nA) CuSO4<\/sub> \u2022 2 H2<\/sub>O
                                              \nB) CaSO4<\/sub> \u2022 \u00bd H2<\/sub>O
                                              \nC) CuSO4<\/sub> \u2022 5 H2<\/sub>O
                                              \nD) CaSO4<\/sub> \u2022 2 H2<\/sub>O
                                              \nAnswer:
                                              \nD) CaSO4<\/sub> \u2022 2 H2<\/sub>O<\/p>\n

                                              4. The oil used in the froth flotation process is
                                              \nA) kerosene oil
                                              \nB) pine oil
                                              \nC) coconut oil
                                              \nD) olive oil
                                              \nAnswer:
                                              \nB) pine oil<\/p>\n

                                              5. Froth flotation is method used for the purification of ………………. ore.
                                              \nA) sulphide
                                              \nB) oxide
                                              \nC) carbonate
                                              \nD) nitrate
                                              \nAnswer:
                                              \nA) sulphide<\/p>\n

                                              6. Galena is an ore of ………………..
                                              \nA) Zn
                                              \nB) Pb
                                              \nC) Hg
                                              \nD) Al
                                              \nAnswer:
                                              \nB) Pb<\/p>\n

                                              7. The metal that occurs in the native form is ………………
                                              \nA) Pb
                                              \nB) Au
                                              \nC) Fe
                                              \nD) Hg
                                              \nAnswer:
                                              \nB) Au<\/p>\n

                                              \"AP<\/p>\n

                                              8. The most abundant metal in the earth’s crust is …………………
                                              \nA) silver
                                              \nB) aluminium
                                              \nC) zinc
                                              \nD) iron
                                              \nAnswer:
                                              \nB) aluminium<\/p>\n

                                              9. The reducing agent in thermite process is ………………….
                                              \nA) Al
                                              \nB) Mg
                                              \nC) Fe
                                              \nD) Si
                                              \nAnswer:
                                              \nA) Oxidise<\/p>\n

                                              10. The purpose of smelting an ore is to ……………….. it.
                                              \nA) Oxidise
                                              \nB) Reduce
                                              \nC) Neutralise
                                              \nD) None of these
                                              \nAnswer:
                                              \nB) Reduce<\/p>\n

                                              10th Class Chemistry 13th Lesson Principles of Metallurgy InText Questions and Answers<\/h3>\n

                                              10th Class Chemistry Textbook Page No. 238<\/span><\/p>\n

                                              Question 1.
                                              \nHow are the metals present in nature?
                                              \nAnswer:
                                              \nSome metals like gold (Au), silver (Ag) and copper (Cu) are available in nature in free sjate. Other metals mostly are found in nature in the combined form.<\/p>\n

                                              10th Class Chemistry Textbook Page No. 240<\/span><\/p>\n

                                              Question 2.
                                              \nWhat metals can we get from the ores mentioned in the Table – 1?
                                              \nAnswer:
                                              \nThe metals are Aluminium (Al), Copper (Cu), Magnesium (Mg), Silver (Ag), Manganese (Mn), Iron (Fe), Zinc (Zn), Sodium (Na), Mercury (Hg), Lead (Pb), Calcium (Ca).<\/p>\n

                                              Question 3.
                                              \nCan you arrange metals in the order of their reactivity?
                                              \nAnswer:
                                              \nThe order of reactivity is like this : Ag < Cu < Pb < Mn < Fe < Zn < Al < Mg < Ca < Na.<\/p>\n

                                              \"AP<\/p>\n

                                              Question 4.
                                              \nWhat do you notice in Table – 2?
                                              \nAnswer:
                                              \nWe notice that ores of many metals are oxides and sulphides. ______<\/p>\n

                                              Question 5.
                                              \nCan you think how we get these metals from their ores?
                                              \nAnswer:
                                              \nWe can get metals from their ores by using various extracting techniques.<\/p>\n

                                              Question 6.
                                              \nDoes the reactivity of a metal and form of its ore (oxides, sulphides, chlorides, carbonates, sulphates) has any relation with process of extraction?
                                              \nAnswer:
                                              \nYes, they have relation. Metals like K, Na, Ca, Mg and Al are so reactive. They exist in all forms whereas moderate reactive metals like Zn, Fe, Pb, etc. exist as oxides, sulphides and carbonates. The least reactive metals are found even in free state.<\/p>\n

                                              Question 7.
                                              \nHow are metals extracted from mineral ores?
                                              \nAnswer:
                                              \nThe extraction of a metal from its ores involves mainly in three states. They are :<\/p>\n

                                                \n
                                              1. Concentration or Dressing<\/li>\n
                                              2. Extraction of crude metal<\/li>\n
                                              3. Refining or purification of the metal.<\/li>\n<\/ol>\n

                                                10th Class Chemistry Textbook Page No. 248<\/span><\/p>\n

                                                Question 8.
                                                \nDo you know why corrosion occurs?
                                                \nAnswer:
                                                \nCorrosion occurs due to reaction of metal with both air and water.<\/p>\n

                                                \"AP<\/p>\n

                                                Question 9.
                                                \nWhat are the conditions under which iron articles rust?
                                                \nAnswer:
                                                \nIron articles get rust due to both air and water.<\/p>\n

                                                10th Class Chemistry Textbook Page No. 251<\/span><\/p>\n

                                                Question 10.
                                                \nWhat is the role of furnace in metallurgy?
                                                \nAnswer:
                                                \nFurnace is used to carry out pyrochemical process in metallurgy.<\/p>\n

                                                Question 11.
                                                \nHow do furnaces bear large amounts of heat?
                                                \nAnswer:
                                                \nFurnaces have metallic lining. So they bear large heats.<\/p>\n

                                                \"AP<\/p>\n

                                                Question 12.
                                                \nDo all furnaces have same structure?
                                                \nAnswer:
                                                \nNo, they have different structures.<\/p>\n

                                                10th Class Chemistry Textbook Page No. 239<\/span><\/p>\n

                                                Question 13.
                                                \nDo you agree with the statement “All ores are minerals but all minerals need not be ores.? Why?
                                                \nAnswer:<\/p>\n