METALS–10th Science Notes and Question Bank

CHAPTER-15

METALS

Text Book Question and Answers

I. Four alternatives are given to each of the incomplete statements/questions. Choose the answer

1. The following is a metal in liquid state at room temperature

(a)Bromine (b)Mercury (c)Germanium (d)Silicon

Answer: (b)Mercury

2. The following element forms cations.

(a)Sulphur (b)Graphite (c)Manganese (d)Iodine

Answer: (c)Manganese

3. The oxide that can form salt and water with a base as well as with an acid is,

(a)Carbon monoxide (b)Sulphur dioxide (c)Sodium Oxide (d)Aluminium oxide.

Answer: (d)Aluminium oxide.

4. Electron donor among the following is,

(a)Potassium (b)Phosphorus (c)Oxygen (d)Fluorine

Answer: (b)Phosphorus

5. Hydrogen gas is liberated under the following circumstance.

(a)iron kept in boiling water (b)water is poured on hot iron

(c)Steam is passed over red hot red (d)Iron is immersed in cold water.

Answer: (c)Steam is passed over red hot red

6. The metal that cannot liberate hydrogen with dilute acids is,

(a)Sodium (b)Aluminium (c)Copper (d)Potassium

Answer: (c)Copper

7. Lemon juice is served normally in ceramics or glass tumblers instead of metallic tumblers because,

(a)glass and ceramics (b)metallic containers react with the acids of lemon

(c)lemon juice produces combustible hydrogen gas with metallic tumblers

(d)glass and ceramics keep the lemon juice cooler

Answer: (b)metallic containers react with the acids of lemon

8. The following combination of metal and acid liberate sulphur dioxide

(a)Zinc and dilute Nitric acid (b)Zinc and dilute Sulphuric acid

(c)Zinc and Hydrochloric acid (d)Zinc and concentrated Sulphuric acid.

Answer: (d)Zinc and concentrated Sulphuric acid.

II. Fill in the blanks

1. Cu + 2H₂SO₄ ------> CuSO₄ + 2H₂O + SO₂

2. 2Na + 2H₂O -------> 2NaOH + H₂

3. The alloy that has least coefficient of linear expansion is Invar

4. Germanium is purified by the technique Zone refining or fractional crystallization

5. Reducing agent used in the extraction of iron is Coke

III. State whether the following statements are true or false

1. Gold occurs in native form - True

2. Sodium is always found in compound state - False

3. Mercury can displace hydrogen from dilute acids - False

4. Ornamental gold is not an alloy - False

5. Iron becomes passive when immersed in concentrated nitric acid - True

IV. Match the following

1. Haematite - Oxide

2. Copper pyrites - Sulphate

3. Limestone - Carbonate

4. Common salt – Chloride

V. Give reasons for the following

1. Magnesium ribbon should not be kept near bottles containing volatile chemicals.

Magnesium is highly reactive hence it should not be placed near bottles with volatile chemicals.

2. Aluminium becomes passive when dipped in concentrated nitric acid.

Aluminium becomes passive when dipped in concentrated nitric acid due to the formation of protective oxide layer on the metal instantly.

3. Limestone and coke are used in the extraction of Iron form Haematite.

Limestone helps in the removal of silica from the ore in the form of calcium silicate slag. Coke is used as it is a cheaper reducing agent.

4. Nitric acid is not normally used to prepare hydrogen gas in the laboratory.

Nitric acid has to be diluted to a great extent as it is a good oxidizing agent hence it is not normally used

5. Aluminium cannot be extracted by heating bauxite and coke.

This is because oxygen of aluminium oxide cannot be easily taken away by reducing agents like coke as aluminium has greater affinity towards oxygen.

6. Tin is used to coat the inner walls of brass and copper utensils.

Coating brass and copper utensils with tin avoids oxidation of brass and copper.

VI. Answer the following questions

1. Name any two ores of Iron

i. Haematite ii. Magnetite

2. Name the constituents of the alloy stainless steel.

The constituent are Iron, Carbon, Chromium and Nickel.

3. Name any three methods of refining a metal

The methods of refining a metal are

i. Fractional crystallization or zone refining

ii. Vacuum melting

iii. Chemical vapour deposition

iv. Liquation process

v. Electrolytic refining

4. Write a neat diagram of blast furnace and label the parts.

5. Write balanced equation of the reaction taking place between copper and moderately concentrated nitric acid when heated.

Copper + moderately diluted nitric acid ---> copper nitrate + nitric oxide + water.

3Cu + 8HNO₃ ---> 3Cu(NO₃)₂ + 2NO + 4H₂O

6. Draw a neat diagram of the apparatus used in the extraction of aluminium from bauxite and label the parts.

Additional Questions

1. Distinguish between a metal and a non metal in physical properties.

Metal	Non metal
Solids at room temperature	Occur in all the three states namely, solid, liquid and gaseous state
Sonorous	Non sonorous
Generally malleable and ductile	Brittle
Generally conduct electricity conductivity differs from metal to metal	Do not conduct electricity
Generally conduct heat	Do not conduct heat
Lustrous	Non lustrous

2. Distinguish between a metal and non metal in chemical properties

Metal	Non metal
Electron donors and hence electropositive	Electron acceptors and hence electronegative
Generally form ionic bond	Generally form both ionic and covalent bond
Generally displace hydrogen form dilute acids	Do not displace hydrogen from dilute acids
Aqueous solutions of metallic oxides turn red litmus blue. Metallic oxides are basic, oxides of zinc and aluminium are amphoteric in the sense that they form salt and water with a base as well as with an acid.	Aqueous solutions of non-metallic oxides turn blue litmus red. Non-metallic oxides are acidic. Non-metallic oxides such as nitrous oxides, carbon monoxide are neutral oxides. They do not dissolve in water.
Some oxides of metals in aqueous solution react with zinc to produce hydrogen	Aqueous solutions of oxides of non-metals react with carbonates producing carbon dioxide.

3. Write the action of other non metals on metals.

a) 3Mg(magnesium) + N₂ (Nitrides) ----> Mg₃N₂ (Magnesium nitride)

b) Ca (Calcium) + H₂(Hydrogen) ---> CaH₂(calcium hydride)

c) 2Al(Aluminium) + 3Cl₂(Chlorine) ----> 2AlCl₃ (Aluminium Chloride)

d) Fe(Ferrous) + S(Sulphur) ---> FeS (Ferrous sulphide)

4. Write the action of concentrated sulphuric acid on metals

a) Cu + 2H₂SO₄ ----> CuSO₄ + SO₂ + 2H₂O

b) Zn + 2H₂SO₄ ----> ZnSO₄ + SO₂ + 2H₂O

5. Write the action of very dilute nitric acid on metals.

Very dilute nitric acid reacts with magnesium metals to liberate hydrogen gas

Mg + 2HNO₃ ---> Mg(NO₃)₂ + H₂

Copper + moderately diluted nitric acid ----> copper nitrate + nitric oxide + water.

3Cu + 8HNO₃ -----> 3Cu(NO₃)₂ + 2NO + 4H₂O

Copper + concentrated nitric acid -----> copper nitrate + nitrogen dioxide + water.

Cu + 4HNO₃ ------> Cu(NO₃)₂ + 2NO₂ + H₂O

6. Write the displacement reaction of metals.

CuSO₄ + Fe -----> FeSO₄ + Cu

7. Name the metals that are available in Free State in nature.

i. Gold ii. Silver iii. Platinum

8. Name the oxide ores, sulphide ores and carbonate ores

Oxide ores – Bauxite, Haematite, Limonite, Magnetite and cuprite.

Sulphide ores – Copper glance, Copper pyrites or Chalco pyrites and Iron pyrites.

Carbonate ores – Siderite, Azurite, Malachite and lime stone.

9. List the metallic ores of Karnataka

10. Define the following (a)Metallurgy (b) gangue (c) Roasting (d) calcination (e)Concentration of the ore. (f) Flux.

(a)Metallurgy: The technology of extraction of metals from their ores and refining to the required from is metallurgy

(b)gangue: The unwanted impurities present in the ore are called gangue particles.

(c)Roasting: Roasting is the process of heating the ore just below its melting point in the presence of air.

(d)Calcination: Calcination is a process of heating the ore just below its melting point in the absence of air.

(e)Concentration of the ore: It is a process of concentrated by removing unwanted impurities.

(f)Flux: Flux is a substance that is added to the ores before heating with a purpose of removing certain unwanted impurities which are not removed during the concentration of ore.

11. Define Slag

Flux combines with the impurities and forms a compound called slag.

12. What is pig iron? Name the other name of pig iron.

The molten iron is converted into solid blocks called pig iron. Other name of pig iron is cast iron.

13. What is an alloy?

Alloy is a homogeneous mixture of (a) two or more metals, or (b) metals and non-metals in suitable proportion.

14. Write the constituents of commonly used alloys

15. Draw neat diagram of Electrolytic refining of copper and label the parts.

16. What is the action of the following metals with oxygen of air? Write the equations.

a) Sodium b) Copper c) Magnesium d)Aluminium

Metals generally react with different components of the air. Different metals react in different ways under different conditions. They react with oxygen of air to produce their respective oxides.

a) Sodium: Sodium reacts with the component of air gradually to produce sodium carbonate.

4Na + O₂ ®2Na₂O

Na2O + CO₂ ®Na₂CO₃

When sodium burns in excess of oxygen, it produces sodium peroxide

2Na + O₂ ®Na₂O₂

b) Copper: Copper reacts with the air to produce is an oxide of copper.

2Cu + O₂ ® 2CuO

c) Magnesium: Magnesium reacts with the air to produced magnesium oxide.

2Mg + O₂ ®2MgO

d) Aluminium: Aluminium reacts with the air to produced aluminium oxide

4Al + 3O₂ ----> 2Al₂O₃

17. Which compound to require for iron to rust?

Air and Water are required for iron to rust.

18. What is rust? Write its chemical formula.

The rust is hydrated oxide of iron. The chemical formula of rust is Fe₂O₃2H₂O.

19. How to Iron is protected from rust.

Iron is protected from rusting by coating it with zinc or by painting it. Iron pipes are protected by heating and then dipping them in molten coal tar.

20. What is the action of the following metals with water? Write the equations.

a) Sodium b) Zinc c) Magnesium d) Iron

When metals react with water, hydrogen is liberated.

a) Sodium: Sodium Metal reacts with water to produced sodium hydroxide and hydrogen gas.

2Na + 2H₂O ®2NaOH + H₂­

b) Zinc: Zinc metal reacts with water to produced zinc oxide and hydrogen gas.

Zn + H₂O ®ZnO + H₂­

c) Magnesium: Magnesium metal reacts with water to produced magnesium oxide and hydrogen gas.

Mg + H₂O®MgO + H₂­

d) Iron: Iron is reacts with water to produced Ferric oxide and hydrogen gas.

3Fe + 4H₂O®Fe₃O₄ + 4H₂­

21. What is the action of the following metals with dilute hydrochloric acid? Write the equations.

a) Zinc b) magnesium c) iron

Metals react with dilute hydrochloric acid to produce hydrogen with the formation of their respective metallic chlorides.

a) Zinc: Zinc metals react with dilute hydrochloric acid to produce zinc chloride and hydrogen gas.

Zn + 2HCl ®ZnCl₂ + H₂ ­

b) Magnesium: Magnesium metals react with dilute hydrochloric acid to produce Magnesium chloride and hydrogen gas.

Mg + 2HCl ® MgCl₂ + H₂ ­

c) Iron: Iron metals react with dilute hydrochloric acid to produce Ferric chloride and hydrogen gas.

2Fe + 6HCl ®2 FeCl₃ + 3H₂­

22. What is the action of the following metals with dilute sulphuric acid? Write the equations.

a) Zinc b) magnesium c) iron

Metals react with dilute sulphuric acid to produce hydrogen with the formation of their respective metallic sulphates.

a) Zinc: Zinc metals react with dilute sulphuric acid to produce zinc sulphate and hydrogen gas.

Zn + H₂SO₄ ®ZnSO₄ + H₂­

b) Magnesium: Magnesium metals react with dilute sulphuric acid to produce Magnesium sulphate and hydrogen gas.

Mg + H₂SO₄ ®Mg SO₄ + H₂­

c) Iron: Iron metals react with dilute sulphuric acid to produce Ferric sulphate and hydrogen gas.

Fe + H₂SO₄ ®Fe SO₄ + H₂­

23. What is the action of the following metals with nitric acid? Write the equations.

a) Zinc b) magnesium c) copper

Metals react with nitric acid to produce hydrogen with the formation of their respective metallic nitrates.

Zn + 2HNO₃ ®Zn (NO₃)₂ + H₂­

Mg + 2HNO₃ ®Mg (NO₃)₂ + H₂­

Metals produce nitrates and nitric oxide with moderately concentrated nitric acid.

3Cu + 8 HNO₃ ®3 Cu ((NO₃)₂ + 2NO + 4H₂O

Metals produce metallic nitrates and nitrogen dioxide with concentrated nitric acid.

Cu + 4HNO₃ ®Cu (NO₃)₂ + 2NO₂­+ 2H₂O

Copper produces cupric nitrate with nitric acid.

24. What is the action of the following metals with chlorine? Write the equations.

a) Aluminium b) Iron c) copper

Metals react with chlorine to form of their respective metallic chlorides.

2Al + 3Cl₂ ®2AlCl₃.

2Fe + 3Cl₂ ®2FeCl₃

Cu + Cl₂ ®CuCl₂

25. Identify the group and period of those metals in the periodic table.

a) Copper b) iron

a) Copper – 11^th groups, 4^th period.

b) Iron – 8^th groups, 4^th period.

26. Write the atomic number, mass number, symbol and electronic configuration, of a copper atom.

Atomic number- 29

Mass number – 64

Symbol – Cu

Electronic configuration – 1s²2s²2p⁶3s²3p⁶3d¹⁰4s¹

27. Write the atomic number, mass number, symbol and electronic configuration of an iron atom.

Atomic number- 26

Mass number – 56

Symbol – Fe

Electronic configuration – 1s²2s²2p⁶3s²3p⁶3d⁶4s²

28. Name the ores of copper.

The chief ore of copper is copper pyrites (CuFeS₂). The other ores are copper glance (Cu₂S), Cuprite (Cu₂O), malachite [CuCO₃Cu(OH)₂] and azurite [2CuCO₃Cu(OH)₂]

29. Name the ores of iron.

The ores of iron are: haematite (Fe₂O₃), magnetite (Fe₃O₄), limonite (Fe₂O₃ H₂O) and siderite (FeCO₃).

30. Explain the method of concentration of copper ore.

The finely powdered ore is mixed with pine oil and water in a large tank. The sulphide ore mixes with oil and forms a thin film. Oil does not have affinity for earthly materials. The materials other than the ore particles are wetted by water. When air is bubbled through the mixture, froth containing the particles of copper ore floats on top of water and can be skimmed off easily. This method, used to concentrate copper ore, is called froth flotation.

31. Name any four alloys of each of the metals: a) copper b) iron

a) Copper

Alloy	Components	Uses
Brass	Copper and zinc	Utensils, electrical appliances, machinery parts etc.
Bronze	Copper and tin	Statues, bells, coins and utensils.
German silver	Copper, zinc and nickel	Utensils, resistance coils, ornamental wares.
Gun metal	Copper, tin and zinc	Barrels of guns, gears and castings.

b) Iron

Alloy	Components	Uses
Stainless steel	Iron, carbon, nickel, chromium	Surgical instruments
Nickel steel	Iron and nickel	Utensils drilling instruments
Alnico	Iron, nickel, aluminium, cobalt	Magnets
Invar steel	Iron, nickel, carbon	Making pendulum
Nichrome	Iron, nickel, chromium	Heating coils.
Steel	Iron, carbon	Pipes, nails, sheets and cutting tools.

32. Show with an example that iron is capable of displacing less reactive metals from the solution of their salts.

Eg1: Iron displaces copper from copper sulphate solution and itself forms iron sulphate. This shows copper is less reactive than iron.

Fe + CuSO₄ ®FeSO₄ + Cu¯

Eg2: Iron displaces silver from silver nitrate solution and itself forms ferrous nitrate. This proves that iron is more reactive than silver.

Fe + 2AgNo₃ ® Fe (No₃)₂ + 2Ag¯

33. What is meant by froth flotation?

The method of concentration of copper ore by using water and oil is known as forth flotation.

34. Explain the method of purification of copper

Purification of copper is done by electrolytic refining. A set of thick impure copper plates are connected together and dipped in copper sulphate solution taken in a tank. Copper sulphate is the electrolyte. A set of thin pure copper plates are connected together and dipped into the same solution such that the pure copper plates are interposed between the impure copper plates

The set of pure copper plates is made cathode and the set of impure copper plates is made anode. This is done by connecting the sets to appropriate terminals of a battery. On passing direct current copper at the anode dissolves and get deposited on the cathode. The mass of cathode plates increases and that of anode plates decreases. Copper so obtained is 100% pure.

35. Write the Physical properties of copper and Iron.

Physical properties of copper: Copper is a rose red heavy metal. It is malleable and ductile. It is a very good conductor of electricity and heat. It is next only to silver in thermal conductivity. It has high melting point and high boiling point.

Physical properties: Iron is a greyish white solid metal. Pure iron is soft. Iron is a ferromagnetic substance. Its melting point is 1808K.

36. Explain the method of extraction of iron

Haematite is powdered and washed in a current of water to remove the unwanted earthly impurities. The earthly impurities such as sand, clay, organic wastes are called gangue. Even after removing some of the gangue materials, the ore would contain silicon dioxide as impurity.

To extract iron from haematite the following materials are needed. They are haematite (Fe2O3), lime stone (CaCO3) and coke (C).

The concentrated haematite, limestone and coke are mixed in the ratio 8:1:4. This mixture is called charge. The mixture is introduced into the blast furnace from the top of the furnace by the cup and cone arrangement. Hot air is blasted from bottom of the furnace. The following reactions take place and finally iron is produced.

1. Lime stone decomposes to calcium oxide

CaCO₃----heat-à CaO + CO₂.

Calcium oxide reacts with silica to forms calcium silicate

CaO + SiO₂------> CaSiO₃

2. Coke reacts with oxygen present in the air to form carbon dioxide

C + O₂------> CO₂.

3. Carbon dioxide reacts with more coke to produce carbon monoxide

CO₂ + C ------> 2CO.

4. Carbon monoxide reduces the iron oxide to iron

Fe₂O₃ + 3CO ------> 2Fe + 3CO₂.

Iron so produced will be in molten state and is collected at the bottom of the furnace.

Calcium silicate is a slag. It collects at the bottom of the furnace above the molten iron. The molten iron and the slag are removed from a separate outlet. Iron so obtained from the blast furnace is called cast iron or pig iron.

You Might Like