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NCERT Exemplar Class 10 Science Chapter 3 Metals and Non-metals Solutions

NCERT Exemplar Solutions for Class 10 Science Chapter 3 Metals and Non-metals covers all the important questions and answers as well as advanced level questions. It helps in learning all the fundamentals of chemical reactions, daily examples of chemical reactions, balancing of chemical reactions and writing of chemical reactions.

The NCERT Exemplar solutions for class 10 science is very important for board exams. NCERT Exemplar Solutions for Class 10 Science Chapter 3 Metals and Non-metals is provided by our experts. They prepared the best solutions which help the students in understanding the solutions in an easy way. This chapters also covers the other topics like type of chemical reactions, oxidation and reduction rusting and different preventive measures.


Chapter Name

Chapter 3 Metals and Non-metals

Book Title

NCERT Exemplar for Class 10 Science

Related Study

  • NCERT Solutions for Class 10 Science Chapter 3 Metals and Non-metals
  • Revision Notes for Class 10 Science Chapter 3 Metals and Non-metals
  • MCQ for Class 10 Science Chapter 3 Metals and Non-metals
  • Important Questions for Class 10 Science Chapter 3 Metals and Non-metals

Topics Covered

  • MCQ
  • Short Answers Questions
  • Long Answers Questions

NCERT Exemplar Solutions for Chapter 3 Metals and Non-metals Class 10 Science

Multiple Choice Questions

1. Which of the following property is generally not shown by metals?

(a) Electrical conduction
(b) Sonorous in nature
(c) Dullness
(d) Ductility

Solution

(c) Dullness 


2. The ability of metals to be drawn into thin wire is known as 
(a) ductility 
(b) malleability
(c) sonorousity
(d) conductivity

Solution

(a) ductility

  • Ductility is property of metals to be drawn into thin wire.
  • Malleability is property of metals to be drawn into thin wire
  • Sonorousity is the ability of metal to be sonorous in nature
  • Conductivity is the ability to conduct electricity 


3. Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point 

(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)

Solution

(d) (i) and (iv) 

Ductility and electric conductivity has no relation to cooking hence thermal conductivity and high melting point are the right answers.


4. Which one of the following metals do not react with cold as well as hot water?
(a) Na
(b) Ca
(c) Mg
(d) Fe

Solution

(d) Fe

Sodium and Calcium react vigorously with cold water whereas magnesium reacts with hot water. Iron does not react with either cold or hot water, it reacts with steam only.


5. Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?
(a) FeO
(b) Fe2O3
(c) Fe3O4
(d) Fe2O3 and Fe3O4

Solution

(c) Fe3O4

3Fe + 4H2O → Fe3O4 + 4H2


6. What happens when calcium is treated with water ? 
(i) It does not react with water
(ii) It reacts violently with water
(iii) It reacts less violently with water 
(iv) Bubbles of hydrogen gas formed stick to the surface of calcium 

(a) (i) and (iv) 
(b) (ii) and (iii) 
(c) (i) and (ii) 
(d) (iii) and (iv) 

Solution

(d) (iii) and (iv) 

Calcium reacts vigorously with water liberates hydrogen.


7. Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg) ?

(a) H2SO4
(b) HCl
(c) HNO3
(d) All of these

Solution

(c) HNO3

Being a powerful oxidizing agent, HNO3 reacts with the metal to form water.

 

8. The composition of aqua-regia is
(a) Dil.HCl : Conc. HNO3 3 : 1
(b) Conc.HCl : Dil. HNO3 3 : 1
(c) Conc.HCl : Conc.HNO3 3 : 1
(d) Dil.HCl : Dil.HNO3 3 : 1

Solution

(c) Conc. HCl : Conc.HNO3 3 : 1


9. Which of the following are not ionic compounds ? 
(i) KCl 
(ii) HCl 
(iii) CCl4 
(iv) NaCl 

(a) (i) and (ii) 
(b) (ii) and (iii) 
(c) (iii) and (iv) 
(d) (i) and (iii) 

Solution

(b) (ii) and (iii) 

HCl and CCl4 are covalent compound hence they cannot be ionic.


10. Which one of the following properties is not generally exhibited by ionic compounds ? 
(a) Solubility in water
(b) Electrical conductivity in solid state 
(c) High melting and boiling points 
(d) Electrial conductivity in molten state 

Solution

(b) Electrical conductivity in solid state

Free ions are not available in solid state in an ionic compound. This is the reason why solid ionic compounds do not conduct electricity.


11. Which of the following metals exist in their native state in nature ? 

(i) Cu 
(ii) Au 
(iii) Zn 
(iv) Ag 

(a) (i) and (ii) 
(b) (ii) and (iii) 
(c) (ii) and (iv) 
(d) (iii) and (iv) 

Solution

(c) (ii) and (iv) 

Gold and silver are non-reactive metals hence they exist in native state.


12. Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining ? 
(i) Au 
(ii) Cu 
(iii) Na 
(iv) K 

(a) (i) and (ii) 
(b) (i) and (iii) 
(c) (ii) and (iii) 
(d) (iii) and (iv) 

Solution

(d (iii) and (iv) 

Sodium and potassium are at the top of there activity series. This is the reason why they can be refined by electrolytic refining.


13. Silver articles become black on prolonged exposure to air. This is due to the formation of
(a) Ag3N
(b) Ag2O
(c) Ag2S
(d) Ag2S and Ag3N

Solution

(c) Ag2S

On exposure to air for prolonged period, silver reacts with sulphurin the atmosphere to form Ag2S. This leads to black coloration of silver articles.


14. Galvanisation is a method of protecting iron from rusting by coating with a thin layer of
(a) Gallium
(b) Aluminium
(c) Zinc
(d) Silver

Solution

(c) Zinc 

In the process of galvanization a layer of zinc is deposited on iron using electrolysis.


15. Stainless steel is very useful material for our life. In stainless steel, iron is mixed with 
(a) Ni and Cr 
(b) Cu and Cr 
(c) Ni and Cu 
(d) Cu and Au 

Solution

(a) Ni and Cr 

Stainless steel is an alloy of Iron, Nicker and chromium. This alloy makes the metal strong, durable and corrosion resistant.


16. If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of
(a) CuSO4
(b) CuCO3
(c) Cu(NO3)2
(d) CuO

Solution

(d) CuO 

Copper reacts to atmospheric oxygen to form a layer of copper oxide which is green in color.


17. Generally, metals are solid in nature. Which one of the following metals is found in liquid state at room temperature?
(a) Na
(b) Fe
(c) Cr
(d) Hg

Solution

(d) Hg

Mercury is a metal which is present in liquid state at room temperature.


18. Which of the following metals are obtained by electrolysis of their chlorides in molten state ? 
(i) Na 
(ii) Ca 
(iii) Fe 
(iv) Cu 

(a) (i) and (iv) 
(b) (iii) and (iv) 
(c) (i) and (iii) 
(d) (i) and (ii) 

Solution

(d) (i) and (ii) 

Sodium and calcium are in the top of the reactivity series.


19. Generally, non - metals are not lustrous. Which of the following nonmetal is lustrous ? 
(a) Sulphur 
(b) Oxygen 
(c) Nitrogen 
(d) Iodine 

Solution

(d) Iodine


20. Which one of the following four metals would be displaced from the solution of its salts by other three metals?
(a) Mg
(b) Ag
(c) Zn
(d) Cu

Solution

(b) Ag 

Silver is a non-reactive metal, hence it can be displaced easily.


21. 2 mL each of concentrated HCl, HNO3  and a mixture of concentrated HCl and concentrated HNO3  in the ratio of 3 : 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put in each test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C respectively. The metal could be

(a) Al 
(b) Au 
(c) Cu 
(d) Pt 

Solution

(b) Au 

Solution C is mixture of concentrated HCl and concentrated HNO3 which is also known as aqua rezia. Gold dissolves in aqua rezia.


22. An alloy is
(a) an element
(b) a compound
(c) a homogeneous mixture
(d) a heterogeneous mixture

Solution

(c) a homogeneous mixture 

The composition of an alloy is uniform hence it is a homogenous mixture.


23.  An electrolytic cell consists of
(i) positively charged cathode
(ii) negatively charged anode
(iii) positively charged anode
(iv) negatively charged cathode

(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (ii) ad (iv)

Solution

(b) (iii) and (iv)

Negatively charged ions move towards the anode. This means that the anode is positively charged.


24. During electrolytic refining of zinc, it gets 
(a) deposited on cathode 
(b) deposited on anode 
(c) deposited on cathode as well as anode 
(d) remains in the solution 

Solution

(a) deposited on cathode 

As zinc is positively charged, it moves towards the negatively charged cathode.


25.  An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following
(a) Mg 
(b) Na 
(c) P 
(d) Ca 

Solution

(b) Na 

Sodium can be cut with a knife as it is soft. Sodium also reacts with water and air vigorously. This is the reason why it is kept in kerosene.


26. Alloys are homogeneous mixtures of a metal with a metal or nonmetal. Which among the following alloys contain non-metal as one of its constituents?
(a) Brass
(b) Bronze
(c) Amalgam
(d) Steel

Solution

(d) Steel 

Steel is an alloy made up of carbon and iron where carbon is a non-metal.


27. Which among the following statements is incorrect for magnesium metal?
(a) It burns in oxygen with a dazzling white flame
(b) It reacts with cold water to form magnesium oxide and evolves hydrogen gas
(c) It reacts with hot water to form magnesium hydroxide and evolves hydrogen gas
(d) It reacts with steam to form magnesium hydroxide and evolves hydrogen gas

Solution

(b) It reacts with cold water to form magnesium oxide and evolves hydrogen gas 

Magnesium reacts with cold water to form magnesium hydroxide and hydrogen gas.


28. Which among the following alloys contain mercury as one of its constituents ? 
(a) Stainless steel 
(b) Alnico 
(c) Solder 
(d) Zinc amalgam 

Solution

(d) Zinc amalgam 

Zinc amalgam is an alloy of mercury and zinc.


29. Reaction between X and Y, forms compound Z. X loses electron and Y gains electron. Which of the following properties is not shown by Z?
(a) Has high melting point
(b) Has low melting point
(c) Conducts electricity in molten state
(d) Occurs as solid

Solution

(b) Has low melting point 

Z is an ionic compound and ionic compounds have high melting point.


30. The electronic configurations of three elements X, Y and Z are X — 2, 8; Y — 2, 8, 7 and Z — 2, 8, 2. Which of the following is correct?
(a) X is a metal
(b) Y is a metal
(c) Z is a non-metal
(d) Y is a non-metal and Z is a metal

Solution

(d) Y is a non-metal and Z is a metal

As Element Y has 3 electron in its outer shell, it is electronegative in nature. Z has 2 electrons in its outermost shell therefore it is electropositive and hence it is a metal.


31. Although metals form basic oxides, which of the following metals form an amphoteric oxide ? 
(a) Na  
(b) Ca 
(c) Al 
(d) Cu 

Solution

(c) Al 

Oxides of Aluminum are both acidic and basic in nature. Hence, aluminum oxides are amphoteric in nature.


32. Generally, non - metals are not conductors of electricity. Which of the following is a good conductor of electricity ? 
(a) Diamond 
(b) Graphite 
(c) Sulphur 
(d) Fullerene 

Solution

(b) Graphite


33. Electrical wires have a coating of an insulting material. The material, generally used is 
(a) Sulphur 
(b) Graphite 
(c) PVC 
(d) All can be used 

Solution

(c) PVC 

As sulphur is brittle in nature, it can be used as an insulating material. Graphite is a good conductor of electricity hence it cannot be used as insulator.


34. Which of the following non-metals is a liquid?
(a) Carbon
(b) Bromine
(c) Phosphorus
(d) Sulphur

Solution

(b) Bromine


35. Which of the following can undergo a chemical reaction?
(a) MgSO4 + Fe
(b) ZnSO4 + Fe
(c) MgSO4 + Pb
(d) CuSO4 + Fe

Solution

(d) CuSO4 + Fe

Iron being more reactive than copper, displaces copper in the reaction to form FeSO4.


36. Which one of the following figures correctly describes the process of electrolytic refining ?

Solution
From the positively charged anode, copper ions are dispersed and deposited on the negatively charged cathode.

Short Answer Questions 

37. Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both the reactions.

Solution

In order to identify the produced gas, light a matchstick and bring it near the gas. If match stick burns with a “pop” sound, it indicates the gas evolved is Hydrogen.
M+ 2NaOH  Na2MO2  + H2
With HCl
M+ 2HCl  MCl2 + H2


38. During extraction of metals, electolytic refining is used to obtain pure metals.
(a) Which material will be used as anode and cathode for refining of silver metal by this process?
(b) Suggest a suitable electrolyte also.
(c) In this electrolytic cell, where do we get pure silver after passing electric current?
Solution
(a) For refining silver metal by this electrolytic refining, impure metal isused as theanode, and pure metal is used as the cathode.
(b) Silver Sulphateor Silver Nitratecan be most suitable electrolyte.
(c) Pure silver is obtained atthe cathode.


39. Why should the metal sulphides and carbonates be converted to metal oxides in the process of extraction of metal from them ?

Solution

It is easier to obtain metal from its oxide, as compared from its sulphides and carbonates.


40. Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg), treated with HNO3 , hydrogen is not liberated, why?

Solution

HNO3 is a strong oxidizing agent. HNO3 oxidises the liberated hydrogen into the water and itself gets converted to nitrogen oxide.


41.  Compound X and aluminium are used to join railway tracks. (a) Identify the compound X (b) Name the reaction (c) Write down its reaction.

Solution

(a) Compound X is Fe2O3  

(b) The reaction involved is a thermite reaction. It is also called as aluminothermy. 
(c) Fe2O3(s)  + 2Al(s) → Al2O3(s) + 2Fe(s) + Heat


42. When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.

Solution

As the molecular mass of NaOH is 40, X is Sodium (Na). Therefore, Y is NaOH. Z is hydrogen as it easily catches fire. The balanced reaction involved is:
2Na + 2H2O → 2NaOH + H2


43. A non - metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.

Solution

  • X -Carbon
  • Y -Diamond
  • Z -Graphite


44. The following reaction takes place when aluminium powder is heated with MnO2  
3MnO2 (s) + 4 Al(s) → 3Mn(I) + 2Al2O3 (I) + Heat
(a) Is aluminium getting reduced ?
(b) Is MnO2  getting oxidised ?

Solution

(a) No, aluminium is not getting reduced as oxygen is added to aluminium. Aluminium is getting oxidised.

(b) No, manganese is not getting oxidised as it has lost oxygen. As a result, manganese is getting reduced.


45. What are the constituents of solder ally ? Which property of solder makes it suitable for welding electrical wires ?

Solution

Solder is an alloy of lead and tin. Low melting point of solder makes it suitable for welding electrical wires.


46. A metal A, which is used in thermite process, when heated with oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCl and NaOH.

Solution

Metal A is aluminium and B is Al2O3 
With HCl
Al2O3 + 6HCl → 2AlCl3 + 3H2O
With NaOH
Al2O3 + 2NaOH → 2NaAlO2 + H2O


47. A metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved.

Solution

By reducing the sulphides or oxides of metals with low reactivity, pure metals can be obtained. The only metal which exists as a liquid at room temperature is mercury. It can be obtained by heating cinnabar (HgS) that is the sulphide ore of mercury. The reactions are as follows:
2HgS + 3O2 →  2HgO + 2SO2 
Mercuric oxide is again heated to get Mercury and Oxygen
2HgO Hg + O2


48. Give the formulae of the stable binary compounds that would be formed by the combination of following pairs of elements.
(a) Mg and N2
(b) Li and O2
(c) Al and Cl2
(d) K and O2

Solution

(a) Magnessium Nitride (Mg3N2)
(b) Lithium Oxide (Li2O)
(c) Aluminium Chloride (AlCl3 )
(d) Potassium Oxide (K2O)


49. What happens when:
(a) ZnCO3 is heated in the absence of oxygen?
(b) a mixture of Cu2O and Cu2S is heated?

Solution

(a) Zinc Oxide and Carbon-di-oxide are liberated when ZnCO3 is heated in the absence of oxygen.
ZnCO3 → ZnO + CO2 
(b) Pure copper is obtained when a mixture of Cu2O and Cu2S is heated. 
2Cu2O + Cu2S → 6Cu + SO2 


50. A non - metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas C causes global warming 
(a) Identify A, B and C 
(b) To which Group of Periodic Table does A belong ?

Solution

(a) A -carbonB -carbon monoxide C -carbon dioxide

(b) A(carbon)belongs to Group –14 of the Periodic Table.


51. Give two examples each of the metals that are good conductors and poor conductors of heat respectively.

Solution

(a) Good conductor : Silver and Copper

(b) Poor conductor : Lead and Mercury


52. Name one metal and one - metal that exist in liquid state at room temperature. Also name two metals having melting point less than 310 K (37°C).

Solution

Mercury(metal)and Bromine(non-metal)are liquid at room temperature. Caesium and Gallium are the metals with melting point less than 310K(37°C).


53. An element A reacts with water to form a compound B which is used in white washing. The compound B on heating forms an oxide C which on treatment with water gives back B. Identify A, B and C and give the reactions involved.

Solution

  • A: calcium
  • B: calcium Hydroxide
  • C: Calcium Oxide. 

Ca + 2H2O → Ca(OH)2 + H2 
Ca(OH)2 → CaO + H2
CaO + H2O → Ca(OH)2 


54. An alkali metal A gives a compound B (molecular mass = 40) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.

Solution

A and B are sodium(Na) and Sodium hydroxide(NaOH) respectively. As the molecular mass of NaOH is 40. C is Sodium aluminate.

Al2O3 + 2NaOH → 2NaAlO2 + H2O


55. Give the reaction involved during extraction of zinc from its ore by (a) roasting of zinc ore(b) calcination of zinc ore.

Solution

(a) Roasting of zinc ore
2ZnS + 3O2 → 2ZnO + 2SO2

(b) Calcination of zinc ore
ZnCO3 → ZnO + CO 


56. A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black colour product. Identify M and black coloured product and also explain the reaction of M with oxygen.

Solution

Copper does not react with acids but with oxygen, it forms Copper Oxide. Therefore, metal M is Copper and black colored product is copper oxide.
2Cu + O2 → 2CuO 


57.  An element forms an oxide A2O3 which is acidic in nature. Identify A as a metal or non - metal.

Solution

As oxides of non-metals are acidic in nature, therefore, A will be a non-metal.


58. A solution of CuSO4 was kept in an iron pot. After few days the iron pot was found to have a number of holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.

Solution

Fe is more reactive thanCu. Therefore, itdisplaces Cu from CuSO4and forms FeSO4.
Fe + CuSO4 → FeSO4 + Cu


Long Answer Questions 

59.  A non-metal A which is the largest constituent of air, when heated with H2 in 1:3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with O2 it gives an oxide C. If this oxide is passed into water in the presence of air it gives an acid D which acts as a strong oxidising agent.
(a) Identify A, B, C and D
(b) To which group of periodic table does this non-metal belong?

Solution

(a) Nitrogen is the largest constituent of air as it constitutes around 78% of the gases, hence non-metal “A” is nitrogen. B is Ammonia, C is Nitrogen-dioxide and D is Nitric acid. When heated with H2in 1:3 ratio in the presence of a catalyst (Fe) following reaction takes place.
3N2 + 3H2 → 2NH3 
On heating Nitrogen with  O2 it gives nitrogen-di-oxide 
N2 + 3O → 2NO2 
When nitrogen-di-oxide is passed into water in the presence of air it gives an Nitric acid 
NO2  + H2O → HNO3

(b) Nitrogen belong to group 15 of the periodic table.


60. Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.

Solution

Ans. During the extraction of metals of low and medium reactivity from their respective sulphide ores. They are first heated in presence of atmospheric oxygen. This step will give out oxides of metal. This step will give out oxides of metal. This step is used as it is more efficient method to extract methods. 

For example: Cinnabar is heated in air to get mercuric sulphide oxidize to produce mercuric oxide. 

2HgS+3O2 → 2HgO+2SO2
Mercuric oxide is further heat to get Mercury
2HgO → 2Hg + O2
Zinc is a metal of medium reactivity and its ore is Zinc Blende
Zinc Blend is roasted to get Zinc oxide
2ZnS + 3O2 → 2ZnO + 2SO2
ZNCO3 → ZnO + CO2
Zinc oxide when heated wit CO2 Zinc is obtained
ZnO + C → Zn + CO


61.  Explain the following
(a) Reactivity of Al decreases if it is dipped in HNO3 
(b) Carbon cannot reduce the oxides of Na or Mg
(c) NaCl is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state
(d) Iron articles are galvanised.
(e) Metals like Na, K, Ca and Mg are never found in their free state in nature.

Solution

(a) If aluminium is dipped in HNO3, it’s reactivity of decreases. This is because HNO3 is a strong oxidizing agent. Therefore, a layer of aluminium oxide gets deposited which I turn reduces the reactivity of aluminium.

(b) Na or Mg are highly reactive metals, hence carbon cannot reduce their oxides. Na and Mg have a higher affinity to oxygen than carbon. Thereby, carbon fails to reduce the oxides of Na and Mg.

(c) In solid state, NaCl is not a conductor of electricity whereas in aqueous solution as well as in molten state NaCl conducts electricity. This is because NaCl is an ionic compound and ionic compounds do not conduct electricity in the solid-state, but they do conduct electricity in aqueous solution and in a molten state.

(d) Iron readily reacts with atmospheric oxygen and forms rust. Iron is galvanized in order to prevent rusting

(e) Na, K, Ca and Mg are highly reactive metals. They can form compounds with almost every element. This is the reason why they are not found in their native form in nature.


62.  (i) Given below are the steps for extraction of copper from its ore. Write the reaction involved.
(a) Roasting of copper (I) sulphide
(b) Reduction of copper (I) oxide with copper (I) sulphide.
(c) Electrolytic refining
(ii) Draw a neat and well labelled diagram for electrolytic refining of copper.

Solution

(i) (a) Roasting of copper (I) sulphide
2Cu2S + 3O2 → 2Cu2O + SO2

(b) Reduction of copper(I) oxide with copper(I) sulphide
2Cu2O + Cu2S → 6Cu + SO2

(c) Reaction for electrolytic refining
At cathode:
Cu2+ + 2e- → Cu
At anode:
Cu → Cu2+ + 2e-


63. Of the three metals X, Y and Z. X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity.
Solution
X is alkali metal as it reacts with cold water. Hence, the element should be either Sodium(Na) or Potassium(K).

  • 2Na + 2H2O → 2NaOH + H2
  • 2K + 2H2O → 2KOH + H2

Y is alkaline earth metal as it reacts with hot water, Hence, it is Magnesium(Mg).
  • Mg + H2O → Mg(OH)2 + H2 
Z reacts with steam only. Hence, it is Iron(Fe).
  • Fe + H2O → Fe2O3 + H2 
Arranging in ascending order (increasing order of reactivity) 
Fe < Mg < Ca 


64. An element A burns with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.
Solution
Element A is 17 Sodium because it will burn with golden flame in air. 
Element B is Chlorine for its atomic number is 17. 
Product C is Sodium Chloride 
2Na + Cl2 → 2NaCl
Product D is Sodium hydroxide 
2NaCl + 2H2O → 2NaOH + Cl2 + H2 

65. Two ores A and B were taken. On heating ore A gives CO2 whereas, ore B gives SO2 . What steps will you take to convert them into metals ? 
Solution
Ore A gives CO2 on heating hence it is a carbonate ore 
Steps : involved in Extraction of ore A 
(a) Calcination 
Ore is heated in limited supply of air to obtain metal oxide 
ACO3 → AO  + CO2  
(b) Reduction 
Metal oxide is reduced with coke to obtain metal. 
AO + C → A + CO 

Ore B is a sulphide ore 
Steps involved in extraction of element B are 
(a) Roasting 
Ore is heating in presence of air to obtain metal oxide 
2BS - 3O2 → 2BO + 2SO2  
(b) Reduction 
Metal oxide is reduced to metal by carbon 
BO + C → B + CO 

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