METALS AND NON-METALS – Chapter Class 10 Science by Teaching Care online tuition and coaching classes

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Metals

The elements that lose electrons and form positive ions are called metals. They are also called electropositive elements e.g. Sodium, Potassium, Calcium, Magnesium, Gold, Silver, Copper, etc.

Hydrogen is a non-metal but it is placed in the group of metals because like metals it also loses electron and form positive ion.

• Physical properties of Metals :

Metals are malleable, ductile, hard, good conductors of heat and electricity and sonorous. They are generally solids and have high melting and boiling points.

• Lustre : The property of an element due to which it has a shiny appearance is called metallic lustre.
• Malleability : The property of metals to be beaten into thin sheets is called malleable metals.
• Ductility : The property of metals to be drawn into thin wire is called ductility. Gold is most ductile metal.
• Following are exceptional metal which :

(a)   Is liquid at room temperature – Mercury.

(b)   Are most malleable – Gold and Silver.

(c)    Are poor conductors of heat – Lead and Mercury.

(d)   Can be cut with knife – Sodium, Potassium, Lithium.

(e)    Is not malleable and ductile – Zinc.

(f)    Have very low melting point – Gallium and Calcium.

(g)    Is most abundant in earth crust – Aluminium.

(h)   React with  and Mn.

(i)    Do not react with water at all – Gold, Silver, Platinum, Lead and Copper.

(j)    React with steam only, Aluminium, iron and Zinc.

(k)   Do not react with oxygen even at high temperature – Gold, Platinum, Silver.

• Chemical properties of metals :

(a)   Metals on burning in air forms basic oxides.

(b)   Metals displace hydrogen from water and steam.

(c)    Metals displace hydrogen from water and dilute acids.

(d)   Metals form ionic chlorides with chlorine.

(e)    Metals do not react with hydrogen. (Only few reactive metals react with hydrogen to form hydrides).

• Hydrogen gas does not evolve when a metal reacts with nitric acid :

Because nitric acid is strong oxidizing agent. It oxidizes the hydrogen gas produced to water and itself gets reduced to any of nitrogen oxides i.e. N₂O, NO or NO₂.

• Non metals : The elements that gain electrons and form negative ions are called non metals. They are also called electronegative elements.

For Example : Chlorine, Sulphur, Oxygen, Bromine, Phosphorus,     Nitrogen, etc.

• Physical and Chemical Properties :

(a)   Non metals are not malleable and ductile but they are brittle.

(b)   Non metals are solid, liquid and gas at room temperature.

(c)    Non metals are not good conductors of heat and electricity.

(d)   Non metals have low melting and boiling points.

(e)    Non metals are soft.

(f)    Non metals from acidic or neutral oxides when react with air.

(g)    Non metals do not react with water and steam.

(h)   Non metals do not displace hydrogen with dilute acids.

(i)    Non metals form covalent chlorides with chlorine.

(j)    Non metals react with hydrogen to form stable hydrides.

• Following are exceptional Non metals which :

(a)   Is liquid at room temperature – Bromine.

(b)   Are lustrous – Iodine and Graphite.

(c)    Is hardest – Diamond.

(d)   Are good conductors of electricity – Graphite.

(e)    Is most abundant in earth crust – Oxygen.

(f)    Show allotropy – Carbon, Sulphur and Phosphorus.

They do not conduct electricity because they do not contain ions in molten state.

• Amphoteric oxides :

The metal oxides which show the properties of both acidic oxides as well as basic oxides. They react with both acids and bases to produce salt and water.

For Example : Aluminium oxide and zinc oxide.

• Alloy :

The homogeneous mixture of a metal with other metal or non metal in molten state is called an alloy.

(a)   Stainless steel is an alloy of iron, nickel and chromium.

(b)   Brass is an alloy of copper and zinc.

(c)    Bronze is an alloy of copper and tin.

(d)   Solder is an alloy of lead and tin.

It has low melting point and is used for welding electrical wires together.

• Properties of Alloy :

(a)   Increase hardness.

(b)   Make resistant to corrosion.

(c)    Decrease melting point.

(d)   Change chemical reactivity.

(e)    Increase colour and tensile strength.

• Allotropy and Allotropes :

The phenomenon in which an element can exist in two or more different physical forms is called allotropy and the different physical forms of an elements are called allotropes.

For Example : Allotropes of carbon are graphite, diamond and Buck minster fullerene.

• Aqua regia : Aqua regia is the mixture of concentrated hydrochloric acid and nitric acid in the ratio 3 : 1. It is called ‘Royal Water’ because it can dissolve Gold and Platinum.
• Reactivity series :

The series of metal in which they are arranged in order of their decreasing reactivity is called reactivity series.

• Reactivity : The tendency of an element to obtain a completely filled outermost shell by losing or gaining electrons is called reactivity.
• Ionic compound :

The compounds formed by losing or gaining electrons or by the transfer of electrons from metal to non metal are called ionic compounds or electrovalent compounds. Ionic bonds are formed between metals and non metals.

For Example : NaCl, MgO, CaCl₂, NaOH, Al₂O₃ etc.

Ionic compounds are very good conductors of electricity.

• Minerals :

The elements and compounds which are found naturally in the earth crust are called minerals.

• Ores : The minerals from which metals can be extracted easily and profitably are called ores. It contains good percentage of metals and less impurities.
• Rusting : The process of depositing a brown flaky substance on the surface of iron due to air and moisture is called rusting. The brown substance is called rust. It is chemically represented Fe₂O₃ ´ H₂

The process of depositing a thick layer of zinc metal on iron objects is called galvanization.

• Chrome plasting : The process of depositing a layer of chromium (Cr) an iron objects is called Chrome plasting.
• Alloying : The process of making homogenous mixture of a metal with other metal or non metal in molten state is called alloying.

All ores are minerals but all minerals are not ores because these may be some minerals from which metals cannot be extracted easily and profitably.

• Gangue : The unwanted materials or the impurities like soil and sand present in ore are called gangue.
• Corrosion : The process of slowly eating away of metals due to their conversion into oxides, carbonates, sulphides, sulphates, etc by the action of moisture and gases is called corrosion.
• Anodizing : The process of forming a thick layer of aluminium oxide over aluminium metal is called anodizing.

 

SOLVED EXAMPLE

 

Example 1:                    

Which metal is the poorest conductor of heat and which one is the best conductor of heat?

Solution:

          Lead is the poorest conductor of heat while silver is the best conductor of heat.

Example 2:

          Name two metals other than silver and gold which are not attacked even by steam.

Solution:

Lead and copper.

Example 3:

          The atom of an element X has the electronic arrangement 2, 8, 2. Without identifying the element, state the valency of the element and write whether it is likely to have oxidizing or reducing properties.

Solution:

          Since the atom has two electrons in the outermost shell, it is a metallic element and is likely to lose these electrons and hence will have reducing properties. By losing two electrons, it will form X²⁺ ions and hence, exhibits a valency of two.

Example 4:

          Which of the following elements is a metal ?

(i)                    (ii)                     (iii)

Solution:

          We observe the number of electrons in the outermost shell. The element which has three or less than three electrons in the outermost shell is metallic.  has eleven electrons. The arrangement of electrons would be 2, 8, 1. It has only one electron in the outermost shell. Hence,  is a metal. Electronic configurations of  and  are 2, 7 and 2, 8 respectively.

Example 5:

          Give the reactions, if any, of the following metals with a solution of copper sulphate :

            (a)   Platinum        (b)   Gold                 (c)    Zinc

Solution:

          Platinum and gold have no reaction. Zinc reacts to form zinc sulphate.

 

Example 6:

          Metal A can displace metal B from BO, the oxide of metal B. Metal B can displace C from solution of CSO₄, the sulphate of metal C. Arrange metals A, B and C in the order of increasing reactivity.

Solution:

          C < B < A is the order of reactivity.

Example 7:

          Give an example of a metal which

(i)    is a liquid at room temperature       (ii)   can be easily cut with a knife ;

(iii)  is the good conductor of heat          (iv)   is the poor conductor of heat.

Solution:

          (i)    Metal which is a liquid at room temperature is Mercury.

(ii)   Alkali metals such as Lithium, Sodium Potassium, etc. can be cut with a knife.

(iii)  Metals which are the good conductor of heat are Silver and Copper.

(iv)   Metals which are the poor conductor of heat are Lead and Mercury.

Example 8:

          Explain the meaning of malleable and ductile.

Solution:

          Metals are malleable because they can be beaten into sheets. Gold and silver are the most malleable metals. Metals are ductile because they can be drawn into wires. Gold and silver are most ductile metals. Gold is so ductile that 1 gram of gold can be drawn into a wire of about 2 kilometre length.

Example 9:

          Why is sodium kept immersed in kerosene oil?

Solution:

          Sodium is a very reactive metal. It reacts with oxygen of the air to form sodium oxide. It also reacts with moisture present in air to form sodium hydroxide and hydrogen. The hydrogen thus produced sometimes catches fire.

          4Na(s)         +         O₂(g)                                                2Na₂O(s)

Sodium                  (from air)                     Sodium oxide

2Na(s)        +          2H₂O(l)                   2NaOH(aq)        +    H₂(g)

Sodium            (from moisture)              Sodium hydroxide         Hydrogen

Therefore, to protect the metal and also to prevent accidental fires, sodium is kept immersed in kerosene oil.

 

Example 10:

          Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H₂SO₄.

Solution:

          When dilute hydrochloric acid is added to a reactive metal like zinc, H₂ gas is produced.

                 Zn(s)    +    2HCl (dilute)        ZnCl₂(aq)   +          H₂(g)

Zinc         Hydrochloric acid            Zinc chloride           Hydrogen

Like zinc, iron is also a reactive metal. Therefore, it reacts with dilute H₂SO₄ to produce H₂ gas.

                 Fe(s)    +    H₂SO₄ (dilute)      FeSO₄(aq)       +    H₂(g)

Iron           Sulphuric acid            Ferrous sulphate     Hydrogen

Example 11:

          An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be

            (a)   Calcium         (b)   Carbon             (c)    Silicon           (d)   Iron

Solution:

          Calcium reacts with oxygen to form calcium oxide. Being ionic compound, it has high melting point. It also dissolves in water to form calcium hydroxide :

                 2 Ca(s)    +    O₂                  2 Ca²⁺ O^2–

Calcium     Oxygen                         Calcium oxide

(Ionic)

                 CaO         +     H₂O                Ca(OH)₂

Calcium oxide Water                      Calcium hydroxide

(Soluble in water)

Thus, option (a) is correct.

On the other hand, the oxide of carbon is CO₂ which is a gas; the oxide of silicon is SiO₂ (silica or sand) which is a high melting solid but is insoluble in water; the oxide of iron is iron oxide or rust, which also has high melting point but is insoluble in water. Thus, options (b), (c) and (d) are wrong.

Example 12:

          Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Solution:

          Metals such as Mg, Al, Zn, Fe, etc. which lie above hydrogen in the activity series are more reactive than hydrogen and hence can displace hydrogen from dilute acids. For example,

Zn (s)          +         H₂SO₄ (aq)                   ZnSO₄(aq)  + H₂(g)

Zinc             Sulphuric acid                Zinc (II) sulphate   Hydrogen

Fe (s)          +         2 HCl (aq)        FeCl₂ (aq)    +         H₂(g)

Iron             Hydrochloric acid            Iron (II) chloride     Hydrogen

Metals such as Cu, Hg, Ag, Au, etc. which lie below hydrogen in the activity series are less reactive than hydrogen and hence cannot displace hydrogen from dilute acids.

Cu, Hg, Ag, Au, etc. .

 

 

EXERCISE

 

LEVEL-I

 

1. Name two metals which are best conductors of heat.
2. Name two metals which can be cut easily with a knife.
3. Name two metals which have very low melting points and melts if you keep them on the palm.
4. Name one metal and one non-metal which exist in liquid state at room temperature.
5. Name the non metal which is Lustrous.
6. What is the nature of oxides formed by metals and non metals?
7. Name two metals which start floating when kept in water.
8. Name two metals other than silver and gold, which do not react with water even in form of steam.
9. Why Sodium and Potassium metals are kept in kerosene?
10. Select a most reactive and a least reactive metal from the following :

Al, Ca, Zn, Fe, Hg, Cu

11. Which two metals liberate hydrogen gas when they react with dilute Nitric acid ?
12. Name two metals which do not react with water but react with steam.
13. What type of chemical bond is present in sodium chloride?
14. Name the process by which metals which are at the top of activity series are extracted from their ore.
15. Name one cheap reducing agent commonly used in extraction of pure metals.
16. Name the reducing agent in the following chemical reaction :

Fe₂O₃ + 2Al ® Al₂O₃ + 2Fe

17. In electrolytic refining, name the electrode which is made of impure metals and the electrode which is made of pure metal.
18. Name the electrolyte used in electrolytic refining of copper.
19. What name is given to the insoluble impurities which settle down at the bottom of the anode during electrolytic refining of metals.
20. Why Aluminium cannot be extracted by reducing alumina with carbon?
21. An element ‘A’ reacts with oxygen to form an oxide which dissolves in water to give an aqueous solution which turns red litmus blue. Element A is metal or non metal?
22. What is an amalgam?
23. Which kind of impurities are present in the ores? What are these impurities collectively known as?
24. Why are the water boilers made of aluminium and copper?
25. Name an alloy which has lower melting point than its constituent.
26. Identify ₁₇X and ₁₁Y as a metal or a non metal.
27. A metal with shining appearance reacts with hot water and also with dilute HCl evolves hydrogen gas. Suggest giving reason why this metal cannot be copper.

 

LEVEL-II

 

1. Except Mg and Mn most of the metals don’t react with HNO₃ to give hydrogen gas. Give reasons.
2. Explain, why magnesium metal after reacting with hot water starts floating on its surface ? Write the chemical equation of the reaction.
3. Describe an activity to show the thermal conductivity of metals.
4. A metal M left in moist air for a longer time, loses its shiny brown surface and gains a green coat. What is this green coloured compound and identify the   metal?
5. Why sodium chloride has high melting point?
6. Give reason : Ionic compounds conduct electricity only in molten state not in solid state.
7. (a)Why aluminium reacts with dil. Hydrochloric acid slowly in the beginning?

    (b)   For making gold ornaments, 22-carat gold is preferred to 24-carat gold. Why?

8. An alloy is used in electronic industry for welding the components. Name the alloy and its constituents.
9. Illustrate the formation of bonds in :

            (a) Sodium chloride

(b) Magnesium chloride

10. Explain why :

(i)  Aluminium is more reactive than Iron, yet its corrosion is less than Iron.

(ii) Carbonate and sulphide ores are usually converted into oxides before reduction during process of extraction.

11. (a) An element A has atomic number 11 and another element B has atomic number 8. A and B combine to form an ionic compound. What would be the formula of the compound formed?

(b) Illustrate the formation of compound showing electron transfer.

 

12. A zinc ore on heating in air gives sulphur dioxide gas. Identify the ore. Define the process that will be utilized in converting this ore to its oxide ore.
13. A metal M is found in nature as MCO₃. It is used in galvanizing iron articles. Name the metal. How can the metal be obtained from its carbonate ore?

LEVEL-III

 

1. Write balanced chemical equations for the reaction taking place when :

(a)   Zinc carbonate is calcinated

(b)   Cinnabar is heated in air

(c)    Manganese dioxide is heated with aluminium powder.

2. Give reason :

(a)   Ionic compounds are solids.

(b)   Gold and silver are found in free state in nature.

(c)    Ionic compounds have high melting points.

3. Write the constituents of following alloys :

(a)   Stainless steel

(b)   Brass

(c)    Bronze

4. What is the reaction between Iron (III) oxide and aluminium known as? Write the chemical equation. Write one use of this reaction.
5. Write the chemical equations for the following reactions :

(a)   Iron reacts with steam.

(b)   Calcium reacts with water.

(c)    Copper is heated in air.

6. Name the ore of Mercury. Name the method by which metals like mercury which are low in the activity series can be extracted from its ore. Write the chemical reactions involved in extraction of mercury from its ore.
7. An element E combines with O₂ to form an oxide E₂O which is a good conductor of electricity. Answer the following :

(a)   How many electrons will be present in the outer most shell of E?

(b)   Write the formula of the compound formed when it combines with Chlorine.

8. A metal ‘M’ has the electronic configuration 2, 8, 3 and occurs in nature as M₂O₃. It is more reactive than zinc. Answer the following questions :

(a)   Name the metal M.

(b)   Name the ore from which this metal is extracted?

(c)    How is this metal oxide converted to metal?

9. What are amphoteric oxides? Give two examples, with chemical equations depicting nature of amphoteric oxides.
10. What are ionic compounds. State four properties of ionic compounds in respect to their physical nature, melting and boiling points, solubility and conduction of electricity?
11. What is meant by rusting? Write an activity to find out the necessary conditions under which iron rusts. Mention two methods used for preventing rusting of Iron.
12. A metal E is stored under kerosene. When a small piece of this metal is left open in the air it starts warning up and the product formed is dissolved in water which turns the red litmus blue :

(a)   Name the metal E.

(b)   Write the chemical equations for the reaction when it is exposed to air and when the product is dissolved in water.

(c)    Explain the process by which the metal is obtained from its molten chloride.

13. What is an alloy? How is an alloy made? List two purposes of making alloys. Mention the constituents of the following alloys : stainless steel, solder.
14. Explain the following with respect to the extraction of metals from their ores :

(a)   Metals at top of the activity series don’t occur in free state in nature.

(b)   Sulphide ores are needed to be roasted after concentration.

(c)    Mercury can be obtained by just roasting ore.

(d)   Highly reactive metals ore obtained by electrolytic reduction of their compound.

(e)    Moderately reactive metals ore obtained by electrolytic reduction of their compound.

15. (a) What would happen when manganese oxide is heated with a reactive metal belonging to group 13 of the periodic table? Write the chemical equation involved.

(b)  Differentiate between roasting and calcinations. Give examples with equations.

16. (a) What is ‘activity series of metals’ ? Arrange the metals Zn, Mg, Al, Cu and Fe in a decreasing order of reactivity.

(b)  What would you observe when you put

(i)  Some zinc pieces into blue copper sulphate solution.

(ii) Some pieces of copper into green ferrous sulphate solution.

(c)  Name a metal which combines with hydrogen gas. Name the compound formed.

17. Explain how the following metals are obtained from their compounds by the reduction process :

(a)   Metal X which is low in the reactivity series.

(b)   Metal Y which is in the middle order of the reactivity series.

(c)    Metal Z which is in high up in the reactivity series.

 

MULTIPLE CHOICE QUESTIONS

 

Pick (Ö) the correct option :

 

1. Because the high electro positivity, the atoms of metals can easily form

(a)   Positive ions                                (b)   Negative ions

(c)    Neutral ions                                (d)   Covalent bonds

2. Metals below hydrogen in the electrochemical series can

(a)   React with acids to liberate hydrogen ions

(b)   React with acids to liberate hydrogen gas

(c)    React with water at ordinary temperature

(d)   None of these

3. Oxides of metals are generally

(a)   Acidic                                         (b)   Basic

(c)    Amphoteric                                 (d)   Neutral

4. The number of electrons in the outermost shell of a non-metal can be

(a)   1, 2, 3 or 4                                  (b)   2, 3, 4 or 5

(c)    4, 5, 6, 7 or 8                              (d)   4, 5, 0 or 2

5. The ordinary sulphur exists as

(a)   S                                                (b)   S₂

(c)    S₄                                               (d)   S₈

6. The lightest element known is

(a)   Helium                                        (b)   Agron

(c)    Hydrogen                                    (d)   Lithium

7. Which of the following metal forms amphoteric oxide ?

(a)   Copper                                        (b)   Silver

(c)    Aluminium                                  (d)   Iron

8. A pinch of sugar is charred when treated with concentrated H₂SO₄. This shows that sulphuric acid is a

(a)   Reducing agent                           (b)   Dehydrating agent

(c)    Dibasic acid                                (d)   Fire producer

 

9. The most abundant non-metal in the earth’s crust is

(a)   Chlorine                                      (b)   Hydrogen

(c)    Silicon                                        (d)   Oxygen

10. Which of the following oxides is neutral?

(a)   P₂O₅                                            (b)   CO₂

(c)    CO                                              (d)   SO₂.

11. Which of the following is the strongest oxidizing agent?

(a)   Oxygen                                        (b)   Nitrogen

(c)    Sodium                                       (d)   Fluorine

12. Which of the following elements is a metalloid?

(a)   Arsenic                                       (b)   Phosphorus

(c)    Hydrogen                                    (d)   Boron

13. Which of the following alloys is a ferrous alloy?

(a)   Bronze                                        (b)   Brass

(c)    Invar                                           (d)   Duralmin

14. During galvanization, the iron is coated with

(a)   Nickel                                         (b)   Zinc

(c)    Aluminium                                  (d)   Chromium

15. Which of the following non-metals is a good reducing agent?

(a)   Chlorine                                      (b)   Hydrogen

(c)    Oxygen                                        (d)   Fluorine

16. Aqua regia is a mixture of

(a)   HNO₃ and HCl in the ratio 1 : 3 by volume

(b)   HNO₃ and HCl in the ratio 3 : 1 by volume

(c)    HNO₃ and H₂SO₄ in the ratio 1 : 1 by volume

(d)   H₂SO₄ and HCl in the ratio 1 : 3 by volume

17. Pure gold is

(a)   14 carat                                      (b)   24 carat

(c)    18 carat                                      (d)   22 carat

18. For making jewellery, gold is mixed with

(a)   Fe                                               (b)   Cu

(c)    Ag                                               (d)   (b) or (c)

19. The process of calcination is used for

(a)   Carbonate ores                            (b)   Sulphide ores

(c)    Nitrate ores                                 (d)   Sulphate ores

20. Which of the following does not conduct electricity?

(a)   Fused NaCl                                 (b)   Solid NaCl

(c)    Brine Solution                             (d)   Copper

 

QUESTIONS BASED ON HIGHER THINKING

 

1. A metal acts as a good reducing agent. It reduces Fe₂O₃, and MnO₂. The reaction with Fe₂O₃ is used for welding broken railway tracks. Identify the metal and write all the chemical reactions.
2. A yellow coloured powder ‘X’ is soluble in carbon disulfide. It burns with a blue flame forming suffocating smelling gas which turns moist blue litmus red. Identify ‘X’ and gives chemical reaction. Identify it is metal or nonmetal.
3. An element reacts with oxygen to form an oxide which dissolves in dilute hydrochloric acid. The oxide formed also turns a solution of red litmus blue. Is the element a metal or non-metal? Explain with the help of a suitable example.
4. Royal water is prepared by mixing two acids ‘A’ and ‘B’. It can dissolve gold and platinium. It is highly corrosive and fuming liquid. Identify ‘A’ and ‘B’. What is the ratio in which ‘A’ and ‘B’ are mixed.
5. Four metals A, B, C and D are, in turn, added to the following solutions one by one. The observations made are tabulated below :

Answer the following questions based on above information.

(i)    Which is the most active metal and why?

(ii)   What would be observed if B is added to a solution of copper (II) sulphate and why?

(iii)  Arrange the metals A, B, C and D in order of increasing reactivity.

(iv)   Container of which metal can be used to store both zinc sulphate solution and silver nitrate solution.

(v)    Which of the above solutions can be easily stored in a container made up of any of these metals?

6. A metal ‘X’ is found in the form of filings which burns vigorously when sprinkle on flame. When these filings are treated with Sulphur a black coloured compound ‘Y’ is formed which is not attracted by magnet. ‘X’ reacts with dil HCl to liberate hydrogen gas. ‘X’ reacts with steam to form ‘Z’ along with hydrogen gas. Identify ‘X’, ‘Y’ and ‘Z’. Write the reaction involved.

A, B and C are 3 elements which undergo chemical reactions according to following equations :

• A₂O₃ + 2B ® B₂O₃ + 2A
• 3CSO₄ + 2B ® B₂ (SO4)_4­ + 3C
• 3CO + 2A ® A₂O₃ + 3C

Answer the following :

(i)    Which element is most reactive?

(ii)   Which element is least reactive?

7. A metal M which is one of the best conductor of heat and electricity is used in making wires is found in nature as sulphide ore M₂S.

(i)    Name the metal M.

(ii)   Which process will be suitable for extraction of this metal from its ore M₂S.

(iii)  Write the balanced chemical reactions involved in the process of extraction.

(iv)   Draw a labeled diagram of electrolytic refining of the metal.

8. E is an element which is one amongst copper, zinc, aluminium and iron. It shows following properties :

(a)   One of its ores is rich in E₂O₃.

(b)   E₂O₃ is not attacked by water.

(c)    It forms two chlorides ECl₂ and ECl₃.

Name the element and justify your answer.

VALUE BASED QUESTIONS

 

1. Gold is a very precious metal. Pure gold is very soft it is therefore not suitable for making jewellery. It is alloyed with either Silver or Copper to make it hard. But sometimes jewelers mix a large quantity of copper and Silver in gold to earn more profit.

(a)   What precautions should you take while purchasing gold jewellery?

(b)   Why does Government insist on purchasing Hall Marked jewellery?

2. Corrosion is a serious problem. Every year an enormous amount of money is spend to replace damaged iron. What steps can be taken to prevent this damage? How can you help your parents at home to prevent this damage?
3. Preety has preferred copper wires than aluminium wires for transmission of electricity. Why she has preferred copper wires? What values does she indicate?
4. Anupam visited the sweet shop he saw that sweets were decorated with silver foils. He told the shopkeeper that it can harm us. How do silver foils harm us? What values are shown by Anupam?
5. Nancy went to purchase steel vessels along with her friend. But her friend suggested her to buy only stainless steel utensils. Why are stainless steel utensils preferred over those of steel? What values are shown by her friend?
6. Vijay is confused he does not know how to join electric wires. Sandeep helped him by jointing the wires using solder. Why is solder preferred for joining electrical wires together? What values are shown by Sandeep?

 

WORKSHEET-1

 

1. (a) Name any one metal which reacts neither with cold water nor with hot water but reacts with heated steam to produce hydrogen gas.

(b) Which one of the following metals does not react with oxygen even at high temperatures? (i) Calcium (ii) Gold (iii) Sodium

2. (a) Name two metals which are both ductile as well as malleable.

(b) Write the chemical equation for the reaction of hot aluminium with steam.

3. (a) What is seen to happen when a piece of sodium metal is dropped into water?

(b) Name any two neutral oxides.

4. (a) Name an ore of zinc other than zinc oxide. By what process can this ore be converted to zinc oxide.

(b) Which one of the following elements symbolized as A and B is a metal: ?

5. An iron knife kept dipped in a blue copper sulphate solution changes to light green. Why?
6. (a) Define the term metallurgy.

(b) Name the iron compound in hematite. Write its chemical formula.

7. (a) Name a non-metallic element which conducts electricity.

(b) Name one non-metal which is liquid at room temperature.

8. (a) What is mineral?

(b) What is an ore?

 

 

WORKSHEET-2

 

1. What is the activity series of metals? Rearrange the following metals in an increasing order of reactivity : Aluminium, Zinc, Mercury.
2. Write chemical equations for the reactions taking place when :

(a)   Zinc sulphide is heated in air.

(b)   Carbon dioxide gas is passed into lime water.

3. Define the term ‘alloy’. Write two advantages of making alloys.
4. Why do we make alloys? State any two reasons.
5. Write chemical equations to show what happens when :

(a)   Manganese dioxide is heated with aluminium.

6. The oxide X₂O₃ is unaffected by water. Outline a method by which a sample of metal X can be obtained from its ore. Give one reason as to why have you chosen this method.
7. Give reasons for the following :

(a)   Metals are regarded as electro positive elements.

(b)   When a piece of Copper metal is added to a solution of zinc sulphate, no change takes place, but the blue colour of copper sulphate fades away when a piece of zinc is placed in its solution.

(c)    Articles made of aluminium do not corrode even though even though aluminium is an active metal.

8. State reasons for the following :

(a)   Metals are good conductors of heat.

(b)   Addition of some silver to pure gold for making ornaments.

(c)    Inability of non-metals for displacing hydrogen from dilute sulphuric acid.

 

 

WORKSHEET-3

1. What is an alloy? Name the constituents of 22-carat gold. Why is 24-carat gold converted to 22-carat gold?
2. Write chemical equations for the reactions taking place when :

(a)   A piece of calcium metal is placed in water.

(b)   Ammonia gas comes in contact with hydrogen chloride gas.

(c)    Sulphur is heated with concentrated H₂SO₄.

3. Write chemical equations to show the reactions taking place when :

(a)   Zinc carbonate is calcined.

(b)   Carbon dioxide gas is bubbled into lime water for a long time.

4. Explain how the following metals are obtained from their compounds by the reduction process :

(a)   Metal ‘X’, which is low in reactivity series

(b)   Metal ‘Y’, which is middle of the series

(c)    Metal ‘Z’, which is high up in the reactivity series.

5. (a) Define the terms, mineral, ore and gangue as used in metallurgical operations.

(b) Describe the method of concentration of a sulphide ore.

6. (a) What is corrosion of metals? Name one metal which does not corrode and one which corrodes on being kept in atmosphere.

(b) How will you show that the rusting of iron needs oxygen and moisture at the same time?

7. (a) Give an example of amalgams.

(b) Define the terms ‘alloy’ and ‘amalgam’. Name the alloy used for welding electric wires together. What are its constituents?

8. Name the constituents of the following alloys :

(a)   Brass             (b)   Stainless steel         (c)    Bronze