Class 10 NCERT Solution Metals and Non-metals

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Question 1:    What is not true about calculations?

(a)to remove all organic matter                        (b)to convert ore into metal

(c)  to remove moisture from the ore              

(d)to decompose carbonates and hydroxides

Question 2:    SO2

(a).  turns dry blue litmus paper red                

(b). turns moist blue litmus paper red

(C) turns moist red litmus paper blue               

 (d)  none of these                  

Question 3:    Which metal is stored in Kerosene Oil in a laboratory?

  1. Magnesium
  2. Copper
  3. Sodium
  4. Zinc

Question 4:    which of the following pairs will give displacement reaction?

(a)NaCl solution and copper metal                             

(b)MgCl2 solution and aluminium metal

(c) FeSO4 solution and silver metal                            

(d)AgNO3 solution and copper metal

Question 5:    what is not true about roasting?

(a)to convert sulphides into oxides     

(b)to remove volatile impurities

(c) to dry the ore    

 (d)to convert the ore into fine powder                             

Question 6:     Metal A when dipped in a solution of a salt of metal B, then metal B is displaced. this shows that

(a).  Metal A is more reactive than metal B         

  (b)Metal B is more reactive than metal A

(C) Metal A and metal B are equally reactive    

  (d) None of these

Question 7:    A non-metallic oxide which is neutral in nature is

 (a)CO2                        (b)CO                          (c) P2O5                     

(d)none of these    

Question 8:    the electro metallurgical process is employed to extract?

(a)Fe                (b)Pb               (c)Na              (d)Ag

Question 9:    An iron nail is dipped in a copper sulphate solution. It is observed that

(a). The colour 0f the solution remain unchanged.    

(b) The colour of the solution becomes red.

(C)The colour 0f the solution turns to light green .    

 (d)  None of these.                                                                                                 

Question 10:    which of the following elements occurs in free in nature

 (a)Co              (b)Fe                (c)Ni                (d)Pt

Question 11:    Which metal reacts less vigorously with water?

  1. Calcium
  2. potassium
  3. sodium
  4. Aluminium

Question 12:    What happens when iron filings are added to dilute hydrochloric acid?  

  1. Iron salt and water is produced.
  2. Chlorine gas is evolved.
  3. Iron oxide is formed.
  4. Hydrogen gas is evolved.

Question 13:    The metal that reacts with hydrogen to form its respective hydride is:

  1. Calcium
  2. Sodium
  3. Potassium
  4. All of these

Question 14:    The liquid Non-metal is?

  1. Iodine
  2. Chlorine
  3. Bromine
  4. Sulphur
  5.                  

Question 15:    The metal that forms amphoteric oxide is?

  1. Cobalt
  2. Sodium
  3. Zinc
  4. Calcium

Question 16:    When zinc is added into the blue colour copper sulphate solution, it turns?

  1. Red
  2. Cyan
  3. Blue
  4. Transparen

Question 17:    When Copper turnings are added into the transparent silver nitrate solution, it turns?

  1. Remains blue
  2. Reddish brown
  3. Black
  4. No effect

Question 18:    -which of the following metals will not react with oxygen, even when heated very strongly in the air?

(a) Zn               (b) Al                           (c)Ag                          (d)Fe

Question 19:    The liquid metal is?

  1. Magnesium
  2. Copper
  3. Mercury
  4. Zinc

Short Answer Questions:

Question 1:   An element X on reacting with

Answer:    Since the oxide turns blue litmus red, therefore X is a non-metal because it is an acidic oxide.

Question 2:   Metals replace hydrogen from acid, whereas non-metals do not. Why?

Answer:    Non-metals cannot supply electrons to convert H+ to H2(g) whereas metals can give electrons to convert

Question 3:   Name the metal which occurs below copper in the reactivity series. Also, name the metal that lies just above hydrogen in the reactivity series

Answer:    Mercury occurs below copper in the reactivity series. Copper is the metal just above hydrogen in the reactivity series.

Question 4:   Why are the two non-metals, carbon and hydrogen are important chemical reference points with regard to the method of metal extraction and reactivity towards acids.

Answer:    The six metals K, Na, Li, Ca, Mg, and Al, which lie above carbon in the activity series, cannot be extracted by carbon reduction: they are usually extracted by electrolysis. Metals below hydrogen i.e., Cu, Ag, Au and Pt, are transition metals that will not displace hydrogen from acids.

Question 5:   Name two metals which can displace hydrogen from dilute HCl.

Answer:    Zinc and Iron

Question 6:   An element X on reacting with oxygen forms an oxide X2O. This oxide dissolves in water and turns blue litmus red. State whether element X is metal or a non-metal.

Answer:    Since the oxide turns blue litmus red, therefore X is a non-metal because it is an acidic oxide.

Question 7:   a) What is the behaviour of magnesium when it is heated and steam is passed over it? Represent the equation. b) Can carbon dioxide react with magnesium?

Answer:    a) When steam is passed over heated magnesium a reaction takes place where a white powder magnesium oxide is formed along with hydrogen. Magnesium will burn with a bright white flame in steam if previously ignited in air.

Question 8:   What are the three major steps involved in the extraction of a metal after its ore is mined?

Answer:    The three steps involved in extraction are:
1) Concentration of the ore to remove impurities.
2) Reduction of the ore to get the metal.
3) Purification of the ore.

Question 9:   Carbonates and sulphide ores are usually converted into oxide ores, why?

Answer:    It is easier to reduce oxide as compared to carbonate and sulphide.

Question 10:   Name the types of reduction processes involved in metallurgy with an example for each.Answer:    The types of reduction processes involved in metallurgy are:
1) Electrolytic reduction of fused compound (chloride or oxide of very active metal).
Example: K, Na, Ca Mg and Al
2) Chemical reduction of oxide by coke only, e.g., Zn is obtained from ZnO by reducing it with coke
3) Chemical reduction of oxide by CO gas, e.g., Fe is obtained from Fe2O3 gas by reducing it by CO gas
4) Self-reduction for Cu extraction

Question 11:   A zinc rod was kept in a glass container having CuSO4solution. On examining, it was found that the blue colour of the solution had faded. After a few days when the zinc rod was taken out of the solution, a number of small holes were noticed in it. State the reason and give the equation of the chemical reaction involved.

Answer:

Zinc has displaced Cu from CuSO4 solution; therefore holes were noticed on a zinc plate.

Question 12:   What is metallurgy?

Answer:    The entire operation, involving all the physical and chemical processes in the extraction of metal from its ore, is called metallurgy.

Question 13:   How does the term “Ore” differ from “Mineral”? Give an example.

Answer:    Minerals are naturally occurring chemical compounds of a metal, which may be associated with more impurities. But ore is a chosen mineral of a metal, from which metal is extracted profitably on a large scale, in pure form. For e.g., the ore of Fe is Haematite, while the minerals having Fe may be magnetite, iron pyrites, etc.

Question 14:   A copper plate was dipped in AgNO3solution. After a certain time, silver from the solution was deposited on the copper plate. State the reason why it happened. Give the chemical equation for the reaction involved.

Answer:    Copper is more reactive than silver, therefore, it displaces silver from silver nitrate

Question 15:   Why is aluminium containers used to transport nitric acid?

Answer:    Aluminium containers are used to transport nitric acid because concentrated HNO3 renders aluminium passive by forming a thin strong protective oxide layer. This protective layer prevents further reaction with the acid.

Question 16:  
1) Why is aluminium used to reduce metal oxides like Fe2O3?
2) What is “Thermite Welding”?Answer:    a) Aluminium is a powerful reducing agent i.e., has a great affinity for oxygen. Hence it reduces metallic oxides below it like Fe2O3 to metal, with the evolution of a lot of heat.
2) The property of aluminium to act as a powerful reducing agent and evolving a lot of heat is used in welding broken iron pieces.

Question 17:   Why is Al obtained only by electrolytic reduction of Alumina (pure)?

Answer:    Aluminium metal has a strong affinity for oxygen and the oxide of Al is Al2O3, which is a very stable oxide. Hence ordinary chemically reducing agents are not sufficient to reduce Al2O3 to Al. Electrolytic reduction is a more powerful reduction method.

Question 18:   Name the two ores of zinc commonly used.

Answer:    The two commonly used ores of zinc are zinc blende (ZnS) and calamine (ZnCO3).

Question19:   Name the following:
1) A metal used in structural engineering
2) A metal used as fuse wire
3) A brittle metal, which is used to galvanise iron
4) A metal whose chloride and sulphate salts are both insoluble
5) A metallic chloride that is soluble in hot water but insoluble in cold water.

Answer:   
1) Iron is used in structural engineering
2) Lead has a low melting point it is therefore used as fuse wire
3) Zinc is the brittle metal used to galvanise iron
4) Lead metal has its chloride precipitate (PbCl2) and sulphate precipitate (PbSO4) as insoluble
5) Lead chloride is insoluble in cold water but dissolves in hot water.

Question20:   Name two metals that occur in a free state nature. What is the method of refining them?

Answer:    Gold and Platinum are two metals that occur in a free in the state in nature. They only need to be cleaned by physical methods.

Question 21:   Give two metallurgical facts that justify placing magnesium above iron in the activity series.

Answer:   
1) Magnesium metal is extracted by electrolytic reduction only, whereas iron can be extracted by chemical reduction using coke. Therefore Mg should be above iron.

2) Magnesium can displace iron from ferrous sulphate solution, but iron cannot displace magnesium from magnesium sulphate solution. Therefore magnesium should be above iron.

Question 22:   In metallurgy, what do the term calculations stand for? Give examples.

Answer:    Calculations is a chemical process wherein a carbonate ore or an oxide ore is strongly heated in the absence of air, to decompose it to remove volatile matter and moisture.

Question 23:   Arrange the following metals in the decreasing order of chemical reactivity; placing the most active first. Cu, Mg, Fe, Na, Ca, Zn.

Answer:    The decreasing order of chemical reactivity is (most active)
Na > Ca > Mg > Zn > Fe > Cu (least active).

Question 24:   How is iron ore reduced in the blast furnace?Answer:    Iron ore is reduced by a powerful reducing agent like carbon monoxide gas.

Question 25: On adding dilute HCl acid to copper oxide powder, the solution formed is blue-green. Predict the new compound formed which imparts a blue-green colour to the solution. CBSE 2008)

Answer: The formed compound is cupric chloride which gives blue-green colour to the solution.

Q26. From amongst the metals sodium, calcium aluminium, copper and magnesium, name the metal

         (i)    which reacts with water only on boiling and

         (ii)    another which does not react even with steam.   (CBSE 2008)

Ans. (i)    Magnesium reacts with water only on boiling.

         (ii)    Copper metal does not react with steam.

Q27. (a)   Show on a diagram the transfer of electrons between the atoms in the formation of MgO.

         (b)   Name the solvent in which ionic compounds are generally soluble.

         (c)   Why are aqueous solutions of ionic compounds able to conduct electricity?                                                              (CBSE 2008)

(b)     Ionic compounds are soluble in water.

         (c)   Ions are present in the aqueous solutions of ionic compounds which can move freely and conduct electricity.

  Q28. (a) Name a metal for each case

    (i)   it does not react with cold as well as hot water but reacts with steam.

     (ii)  it does not react with any physical state of water.

     (b)   When calcium metal is added to water the gas evolved does not catch fire on adding sodium metal to water catches fire. Why is it so?                                                          (A.I. CBSE 2008)

Ans. (a)   (i)   The iron metal reacts only with steam.

                 (ii)  Copper does not react with any state of water.

         (b)   When sodium metal is added to water, it reacts with water as sodium metal is highly reactive and produces sodium hydroxide and hydrogen gas along with a large amount of heat. Due to this large heat hydrogen catches fire.

Q29. (a)   What are amphoteric oxides? Choose the amphoteric oxides from amongst the following oxides?

                 Na2O, ZnO, Al2O3, CO2, H2O.

         (b)   Why is it that non-metals do not displace hydrogen from dilute acids?                                                                                                                  (A.I.CBSE 2008)

Ans. (a)   Amphoteric oxides are those which are acidic as well as basic in nature. Al2O3, H2O and ZnO are amphoteric oxides.

         (b)   Non-metals cannot lose electrons so they do not displace hydrogen from dilute acids.

Q30. Give reasons for the following:

         (a)   Gold and silver are used to make jewellery

         (b)   Carbonate and sulphide gas are usually converted into oxides prior to reduction during the process of extraction.               (CBSE 2008C)

Ans. (a)   Due to highly lustrous, malleable and ductile properties, gold and silver are used to make jewellery.

         (b)   Because the reduction of metal oxides into metals is cheaper and easier than converting carbonate and sulphide are into metals.

Q31. Give reasons for the following                                                                     (CBSE 2008C)

         (a)   Metals can be given different shapes according to our needs.          

         (b)   Hydrogen is not evolved when a metal reacts with nitric acid.

Ans. (a)   Metals can be drawn into sheets and wires as they are malleable and ductile. Therefore, it does not break due to high tensile strength and so it can be used according to our needs.

         (b)   Nitric acid is a strong oxidising agent; when metals react with nitric acid it does not release hydrogen gas as oxidising it to form H2O.

Q32. Which of the following metals will melt at body temperature (37°C)?         (CBSE 2008C)

         Gallium, magnesium, caesium, aluminium.

Ans. Gallium and caesium.

Q33. Give reasons for the following:                                                                    (CBSE 2008C)

         (a)   Aluminium oxide is considered as an amphoteric oxide

         (b)   Ionic compounds conduct electricity in the molten state.

Ans. (a)   Aluminium oxide reacts with acid as well as a base to form a salt. It shows the properties of both acid and base.

         (b)   Ionic compounds produce free ions in a molten sta    te which allows electricity to be produced.

Q34. Name two metals which react violently with cold water. Write any three observations you would make when such a metal is dropped into water. How would you identify that gas evolved if any during the reaction?      (A.I. CBSE 2008)

Ans. Sodium and potassium react violently with cold water.

         When these metals are dropped in water, hydrogen gas evolved in the form of bubbles, and a large amount of heat is produced and the solution will change red litmus blue.

         When bring burning splinter near the mouth of the test tube where gas is evolved, the splinter burns with a pop sound so, hydrogen gas is formed.