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Multiple Choice Questions (MCQs)
- Which of the following is a property of metals?
- (a) Non-conductive
- (b) Brittle
- (c) Ductile
- (d) Insulator
Answer: (c) Ductile
- Which metal is the best conductor of heat?
- (a) Iron
- (b) Copper
- (c) Silver
- (d) Lead
Answer: (c) Silver
- Which metal is liquid at room temperature?
- (a) Mercury
- (b) Sodium
- (c) Lead
- (d) Aluminium
Answer: (a) Mercury
- Which non-metal is a good conductor of electricity?
- (a) Sulphur
- (b) Iodine
- (c) Graphite
- (d) Phosphorus
Answer: (c) Graphite
- Which of the following is not a metal?
- (a) Sodium
- (b) Carbon
- (c) Magnesium
- (d) Aluminium
Answer: (b) Carbon
- Which of the following metals can be cut with a knife?
- (a) Copper
- (b) Sodium
- (c) Iron
- (d) Aluminium
Answer: (b) Sodium
- Which of the following pairs will undergo a displacement reaction?
- (a) CuSO₄ and iron
- (b) ZnSO₄ and copper
- (c) FeSO₄ and copper
- (d) MgSO₄ and iron
Answer: (a) CuSO₄ and iron
- Which of the following methods is used to prevent rusting of iron?
- (a) Painting
- (b) Greasing
- (c) Galvanizing
- (d) All of the above
Answer: (d) All of the above
- Which metal does not react with water at all?
- (a) Sodium
- (b) Magnesium
- (c) Aluminium
- (d) Copper
Answer: (d) Copper
- Which gas is produced when a metal reacts with dilute hydrochloric acid?
- (a) Oxygen
- (b) Hydrogen
- (c) Nitrogen
- (d) Carbon dioxide
Answer: (b) Hydrogen
Short Answer Questions
- What is meant by malleability?
- Answer: Malleability is the property of metals to be beaten into thin sheets.
- What is ductility?
- Answer: Ductility is the property of metals to be drawn into thin wires.
- Why is sodium stored in kerosene?
- Answer: Sodium is stored in kerosene to prevent it from reacting with moisture and oxygen in the air, which could cause it to catch fire.
- Give an example of a metal that is a good conductor of electricity.
- Answer: Copper is a good conductor of electricity.
- Why do metals conduct electricity?
- Answer: Metals conduct electricity because they have free electrons that move easily within the metal structure.
- Why is aluminium used for making cooking utensils?
- Answer: Aluminium is used for making cooking utensils because it is a good conductor of heat and is resistant to corrosion.
- What happens when magnesium burns in air?
- Answer: When magnesium burns in air, it produces a bright white flame and forms magnesium oxide.
- Which metal is more reactive, sodium or calcium?
- Answer: Sodium is more reactive than calcium.
- Why is gold used for making jewelry?
- Answer: Gold is used for making jewelry because it is highly malleable, ductile, and does not corrode.
- What is corrosion?
- Answer: Corrosion is the gradual destruction of metals due to their reaction with oxygen, moisture, and other environmental factors.
Case Study Questions
- Case Study: A metal M reacts vigorously with water and forms a compound X, which is soluble in water. The solution of X in water conducts electricity. Identify M and X.
- Answer: The metal M is sodium (Na), and the compound X is sodium hydroxide (NaOH).
- Case Study: A metal N does not react with cold or hot water but reacts with steam to form an oxide and hydrogen gas. Identify N and the oxide formed.
- Answer: The metal N is iron (Fe), and the oxide formed is iron oxide (Fe₃O₄).
- Case Study: A non-metal O is used in the manufacture of fertilizers. It exists in gaseous form at room temperature. Identify O.
- Answer: The non-metal O is nitrogen (N₂).
- Case Study: A metal P is used in the construction of bridges and buildings. It forms a green layer when exposed to moist air. Identify P and the compound formed.
- Answer: The metal P is copper (Cu), and the compound formed is basic copper carbonate.
- Case Study: A metal Q is often used in the galvanization process to protect iron from rusting. Identify Q.
- Answer: The metal Q is zinc (Zn).
Application-Based Questions
- Why are electrical wires coated with PVC or rubber?
- Answer: Electrical wires are coated with PVC or rubber to insulate them and prevent electrical shocks.
- Explain why school bells are made of metals.
- Answer: School bells are made of metals because metals are sonorous, meaning they produce a ringing sound when struck.
- How does the electronic configuration of sodium explain its reactivity?
- Answer: Sodium has one electron in its outermost shell, making it highly reactive as it easily loses this electron to achieve a stable electronic configuration.
- Why does aluminium not corrode easily even though it is a reactive metal?
- Answer: Aluminium forms a protective oxide layer on its surface when exposed to air, which prevents further corrosion.
- Why is aqua regia used to dissolve gold?
- Answer: Aqua regia is used to dissolve gold because it is a highly corrosive mixture of hydrochloric acid and nitric acid that can dissolve gold, which is otherwise resistant to acids.
True/False Questions
- All metals are solid at room temperature.
Answer: False (Mercury is liquid at room temperature)
- Non-metals are generally good conductors of electricity.
Answer: False (Most non-metals are insulators, except graphite)
- Malleability is the property of metals to be drawn into wires.
Answer: False (Malleability is the property to be beaten into sheets; ductility is for wires)
- Silver is a better conductor of heat than copper.
Answer: True
- Zinc does not react with dilute acids.
Answer: False (Zinc reacts with dilute acids to produce hydrogen gas)
Fill in the Blanks
- Gold is a highly ___________ metal and is used in making jewelry.
- ___________ is a process of coating iron with zinc to prevent rusting.
- Metals like sodium and potassium react vigorously with ___________.
- The ability of metals to produce a sound when struck is called ___________.
- Copper is used in electrical wiring because it is a good ___________.
- Answer: conductor of electricity
Matching Questions
- Match the metal with its use:
- (a) Aluminium – (i) Jewelry
- (b) Iron – (ii) Electrical wiring
- (c) Gold – (iii) Utensils
- (d) Copper – (iv) Construction
Answer: (a) – iii, (b) – iv, (c) – i, (d) – ii
- Match the property with the element:
- (a) Lustrous – (i) Sulphur
- (b) Malleable – (ii) Sodium
- (c) Non-conductive – (iii) Iron
- (d) Ductile – (iv) Graphite
Answer: (a) – iii, (b) – ii, (c) – i, (d) – iv
Long Answer Questions
- Describe the process of electrolytic refining with an example.
- Answer: Electrolytic refining is the process of purifying impure metals using electrolysis. For example, in the electrolytic refining of copper, impure copper is used as the anode, and a pure copper strip is used as the cathode. The electrolyte is a solution of copper sulphate. When electric current is passed, pure copper from the anode dissolves into the solution and deposits on the cathode, leaving impurities as anode mud.
- Explain how metals react with acids and provide the general equation for the reaction.
- Answer: When metals react with acids, they generally produce a salt and hydrogen gas. The general equation is:
Metal + Acid → Salt + Hydrogen gas.
For example, when zinc reacts with hydrochloric acid, the equation is:
Zn + 2HCl → ZnCl₂ + H₂↑
- What is corrosion? How can it be prevented?
- Answer: Corrosion is the process where metals are gradually degraded by their reaction with environmental elements such as oxygen and moisture. It can be prevented by methods such as painting, greasing, galvanization, and alloying.
- Discuss the properties and uses of ionic compounds.
- Answer: Ionic compounds are solid and hard, have high melting and boiling points, are generally soluble in water, and conduct electricity in molten state or when dissolved in water. They are used in various applications such as in electrolytes, in salts, and in manufacturing various chemical compounds.
Conceptual Questions
- Why do metals tend to lose electrons during chemical reactions?
- Answer: Metals tend to lose electrons to achieve a stable electron configuration similar to noble gases, resulting in the formation of positively charged ions.
- Why is it not possible to store sodium in water?
- Answer: Sodium reacts vigorously with water, producing hydrogen gas and a large amount of heat, which can cause fire or explosion. Therefore, it must be stored in kerosene.
- How do the properties of metals relate to their uses in everyday life?
- Answer: Metals are used in everyday life based on their properties. For example, their malleability and ductility make them suitable for manufacturing wires and sheets; their conductivity makes them ideal for electrical wiring; and their strength is utilized in construction.
- Why do ionic compounds have high melting and boiling points?
- Answer: Ionic compounds have high melting and boiling points due to the strong electrostatic forces of attraction between the oppositely charged ions, which require a large amount of energy to break.
Experimental Questions
- Describe an experiment to test the electrical conductivity of a metal.
- Answer: To test the electrical conductivity of a metal, set up an electric circuit with a battery, a bulb, and wires. Insert the metal sample into the circuit. If the bulb glows, the metal is a good conductor of electricity.
- How can you demonstrate that a metal is ductile?
- Answer: Take a metal wire and try to stretch it. If it can be drawn into a thinner wire without breaking, it demonstrates the property of ductility.
- What happens when a metal like magnesium is burnt in air? Describe an experiment to observe this.
- Answer: When magnesium is burnt in air, it burns with a bright white flame and forms magnesium oxide. To observe this, ignite a strip of magnesium ribbon in the flame of a Bunsen burner and observe the intense white light and the powdery white ash (magnesium oxide) formed.
- Explain how the reactivity of metals with acids can be tested experimentally.
- Answer: To test the reactivity of metals with acids, place small pieces of different metals in test tubes containing dilute hydrochloric acid. Observe the rate of bubble formation (hydrogen gas) and the temperature change. More reactive metals will produce bubbles rapidly and the temperature will increase.
Higher Order Thinking Skills (HOTS) Questions
- Why does aluminium not corrode easily even though it is reactive?
- Answer: Aluminium does not corrode easily because it forms a protective oxide layer on its surface when exposed to air, preventing further oxidation.
- Why does iron rust, but stainless steel does not?
- Answer: Iron rusts because it reacts with oxygen and moisture in the air to form iron oxide. Stainless steel, an alloy of iron, contains chromium which forms a protective oxide layer on the surface, preventing rust.
- Explain why certain metals are found in the free state in nature while others are not.
- Answer: Metals like gold, silver, and platinum are found in the free state in nature because they are less reactive and do not easily combine with other elements. More reactive metals, like sodium and potassium, are always found in combined forms as they react readily with other elements.
- Why are alloys often preferred over pure metals in practical applications?
- Answer: Alloys are preferred because they often have superior properties compared to pure metals, such as increased strength, resistance to corrosion, or improved electrical conductivity, making them more suitable for various applications.
Fill in the Blanks
- __________ is a metal that reacts vigorously with cold water.
- The process of forming a protective oxide layer on aluminium is called __________.
- Silver reacts with sulphur in the air to form __________, causing it to tarnish.
- When metals are heated, they generally form __________ oxides.
- Non-metals generally form __________ oxides when combined with oxygen.
True/False
- Non-metals are generally more reactive than metals.
Answer: False (This statement varies depending on the elements being compared.)
- Gold and silver are found in the free state because they are highly reactive.
Answer: False (They are found in the free state because they are less reactive.)
- Alkali metals, like sodium and potassium, are very soft and can be cut with a knife.
Answer: True
- Ionic compounds do not conduct electricity in solid state.
Answer: True
- Aluminium is more reactive than iron, but it does not corrode as easily.
Answer: True
Application-Based Questions
- Why is zinc used in the process of galvanization?
- Answer: Zinc is used in galvanization because it forms a protective layer that prevents rusting, even if the coating is scratched.
- How does the reactivity series help in predicting the outcomes of displacement reactions?
- Answer: The reactivity series arranges metals in order of their reactivity. A more reactive metal will displace a less reactive metal from its compound in a solution, helping predict the result of such reactions.
- Why are copper vessels often cleaned with lemon or tamarind juice?
- Answer: Copper vessels are cleaned with lemon or tamarind juice because these substances contain acids that react with the basic copper oxide (tarnish), removing it and restoring the metal’s shine.
- Explain why magnesium does not react with cold water but reacts with steam.
- Answer: Magnesium does not react with cold water because the reaction is too slow at low temperatures. However, it reacts with steam as the higher temperature provides sufficient energy to initiate the reaction.
Matching Questions
- Match the following metals with their ores:
- (a) Iron – (i) Bauxite
- (b) Aluminium – (ii) Haematite
- (c) Copper – (iii) Galena
- (d) Lead – (iv) Chalcopyrite
Answer: (a) – ii, (b) – i, (c) – iv, (d) – iii
- Match the metal with its protective method:
- (a) Iron – (i) Anodizing
- (b) Aluminium – (ii) Galvanization
- (c) Steel – (iii) Painting
- (d) Copper – (iv) Alloying
Answer: (a) – ii, (b) – i, (c) – iii, (d) – iv
Long Answer Questions
- Describe the extraction process for metals low in the reactivity series.
- Answer: Metals low in the reactivity series, such as mercury and copper, are extracted by heating their ores in the presence of air. For example, mercury is extracted by heating cinnabar (HgS) in air, which first forms mercury oxide (HgO) and then decomposes to produce mercury metal.
- Explain the thermit process and its applications.
- Answer: The thermit process involves the reaction of aluminium powder with iron(III) oxide, producing molten iron and aluminium oxide. This highly exothermic reaction is used in welding and repairing railway tracks.
- How are the properties of ionic compounds related to their uses in everyday life?
- Answer: Ionic compounds, with their high melting and boiling points, are used in high-temperature applications. Their solubility in water makes them useful in various chemical processes. Their electrical conductivity in molten state or in solution is utilized in electroplating and electrolysis.
- Discuss the importance of alloys in industrial applications.
- Answer: Alloys are crucial in industries because they combine desirable properties of different metals, such as strength, corrosion resistance, and electrical conductivity. This makes them suitable for use in construction, electrical components, automotive parts, and more.
Conceptual Questions
- Why does rusting occur more quickly in coastal areas than in dry regions?
- Answer: Rusting occurs more quickly in coastal areas because of the higher humidity and salt content in the air, which accelerates the oxidation process.
- How does alloying improve the properties of metals?
- Answer: Alloying improves the properties of metals by combining them with other elements, which can increase strength, hardness, corrosion resistance, and other desirable traits.
Experimental Questions
- Design an experiment to demonstrate that metals can be drawn into wires.
- Answer: Take a metal rod and attach one end to a weight while pulling the other end steadily with force. If the metal is ductile, it will stretch into a wire without breaking.
- How can you experimentally verify that ionic compounds conduct electricity in molten state but not in solid state?
- Answer: Take an ionic compound in solid state and set up a circuit with a bulb, battery, and wires. Connect the wires to the solid compound, and observe that the bulb does not light up. Now heat the compound to melt it, and reconnect the wires. The bulb will light up, showing that the molten compound conducts electricity.
Higher Order Thinking Skills (HOTS) Questions
- Explain why gold does not tarnish like other metals.
- Answer: Gold does not tarnish because it is highly non-reactive and does not easily form oxides or other compounds with environmental elements like oxygen or sulphur.
- Why is silver nitrate used in chemical reactions to detect the presence of chloride ions?
- Answer: Silver nitrate is used because it reacts with chloride ions to form a white precipitate of silver chloride, which is easily visible, making it an effective test for chloride ions.
- How does the presence of impurities in metals affect their properties?
- Answer: Impurities in metals can alter their properties by making them more brittle, less conductive, or more susceptible to corrosion. They can also affect the metal’s melting point and hardness.
True/False
- Copper can displace silver from silver nitrate solution.
Answer: True
- Alloys have lower melting points than pure metals.
Answer: True
- Zinc reacts with dilute hydrochloric acid to form zinc chloride and hydrogen gas.
Answer: True
- Sulphur is a good conductor of electricity.
Answer: False (Sulphur is a non-metal and a poor conductor of electricity)
- Aluminium is less reactive than iron.
Answer: False (Aluminium is more reactive than iron)
Application-Based Questions
- Why are bridges often made of steel rather than pure iron?
- Answer: Bridges are made of steel because steel is stronger, more durable, and less prone to rusting than pure iron.
- Explain why copper is not used in the construction of buildings despite its high conductivity.
- Answer: Copper is not used in construction due to its high cost, lower strength compared to steel, and susceptibility to corrosion in moist environments.
- Why are aluminium alloys used in the aerospace industry?
- Answer: Aluminium alloys are used in the aerospace industry because they are lightweight, strong, and resistant to corrosion, making them ideal for aircraft construction.
- What would happen if sodium was stored in water instead of kerosene?
- Answer: If sodium was stored in water, it would react violently, producing hydrogen gas and heat, which could cause an explosion or fire.
Matching Questions
- Match the reaction with the observation:
- (a) Magnesium in cold water – (i) Violent reaction
- (b) Iron in steam – (ii) No reaction
- (c) Sodium in water – (iii) Slow reaction
- (d) Zinc in acid – (iv) Bubbles of hydrogen
Answer: (a) – ii, (b) – iii, (c) – i, (d) – iv
- Match the metal with its reactivity:
- (a) Potassium – (i) Least reactive
- (b) Aluminium – (ii) Moderately reactive
- (c) Gold – (iii) Highly reactive
- (d) Zinc – (iv) Less reactive
Answer: (a) – iii, (b) – ii, (c) – i, (d) – iv
Long Answer Questions
- Describe how metals can be protected from corrosion.
- Answer: Metals can be protected from corrosion through methods such as painting, coating with oil or grease, galvanization (coating with zinc), and anodizing (for aluminium). These methods create a barrier that prevents the metal from coming into contact with moisture and oxygen, which cause corrosion.
- Explain the process of electrolysis used in the extraction of highly reactive metals.
- Answer: In the electrolysis process, a highly reactive metal is extracted from its molten chloride. The metal cations migrate to the cathode where they gain electrons and are deposited as pure metal, while anions move to the anode where they lose electrons and form a gas. For example, sodium is extracted from molten sodium chloride using electrolysis.
- Discuss the role of alloys in everyday life.
- Answer: Alloys play a crucial role in everyday life by enhancing the properties of metals for specific applications. For instance, stainless steel (an alloy of iron, chromium, and nickel) is used for cutlery and appliances due to its resistance to rust. Brass (an alloy of copper and zinc) is used in musical instruments and plumbing fixtures for its durability and acoustic properties.
- Compare and contrast the physical and chemical properties of metals and non-metals. – Answer: Metals are generally lustrous, malleable, ductile, and good conductors of heat and electricity. They tend to lose electrons during chemical reactions and form basic oxides. Non-metals, on the other hand, are usually dull, brittle, non-conductive, and gain electrons in reactions to form acidic or neutral oxides. For example, iron (a metal) is shiny, conductive, and forms a basic oxide (iron oxide), while sulfur (a non-metal) is dull, non-conductive, and forms an acidic oxide (sulfur dioxide).
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