1.Define malleability and ductility. Name the two most malleable and two most ductile metals known to us.
2.State the exceptions to the general physical properties of metals regarding their hardness, physical state at room temperature, density, and melting/boiling points.
3.Why are electrical wires in household circuits coated with polyvinyl chloride (PVC) or rubber-like materials? Explain based on physical properties.
4.Contrast the physical properties of metals and non-metals with respect to: (a) hardness, (b) state, (c) lustre, (d) thermal and electrical conductivity, (e) density.
5.Although non-metals are generally soft, dull, non-conductors with low melting points, there are notable exceptions. List three exceptions to these general rules among non-metals.
6.Give scientific reasons for the following observations:
- Silver is the best conductor of electricity, yet copper is used for electrical wiring in houses.
- Sodium and potassium can be cut easily with a kitchen knife.
7.Explain what is meant by the terms: (a) Sonorous metals, (b) Metallic lustre. Give examples of how these properties are used practically.
8.Non-metals generally have low melting and boiling points. Name a non-metal that has an exceptionally high melting and boiling point, and explain why.
9.What happens when a metal plate is hit hard with a heavy iron hammer? What specific physical property of metals does this demonstrate?
10.Is malleability a characteristic property of non-metals? What happens when a solid piece of sulphur is struck with a hammer? Explain the physical behavior of non-metals under stress.
11.What happens when a copper wire is heated strongly in air? Write the balanced chemical equation and state the change in appearance of the wire.
12.Why is sodium metal kept immersed in kerosene oil? What would happen if a piece of sodium metal is left exposed to air or dropped in water? Write equations.
13.What are amphoteric oxides? Give two examples of amphoteric oxides and write balanced chemical equations to show their reactions with both hydrochloric acid and sodium hydroxide.
14.Describe how different metals react with water. Specifically write balanced equations and explain why:
- Sodium reacts violently with cold water.
- Calcium floats on the surface of water during the reaction.
- Iron reacts only with steam and not cold or hot water.
15.What gas is evolved when a metal reacts with dilute hydrochloric acid? Write the balanced chemical equation for the reaction of magnesium ribbon with dilute HCl. How will you test this gas?
16.Why is hydrogen gas not evolved when metals (except magnesium and manganese) react with dilute nitric acid ($\text{HNO}_3$)? Explain the chemistry behind this observation.
17.What is Aqua Regia? State its composition, properties, and explain why it is capable of dissolving noble metals like gold and platinum which do not react with any single acid.
18.Write the reactivity series of metals in decreasing order of reactivity. Explain displacement reactions with reference to an iron nail immersed in copper sulphate solution. Write the equation and observations.
19.Write complete balanced equations for the following reactions:
- Aluminium reacting with steam.
- Iron reacting with steam.
- Calcium reacting with water.
20.Why does copper not react with dilute hydrochloric acid even when heated, whereas it reacts with hot concentrated sulphuric acid? Explain.
21.Write the observations and balanced chemical equation when a strip of copper metal is kept immersed in a silver nitrate ($\text{AgNO}_3$) solution for some time.
22.Explain how the reactivity of metals towards oxygen decreases as we move down the reactivity series from sodium to copper. Use examples.
23.What are valence electrons? Why are noble gases chemically inert and do not react with other elements to form compounds?
24.How do metals and non-metals react with each other to achieve a stable octet configuration? Define an ionic (electrovalent) bond.
25.Show the formation of Sodium chloride ($\text{NaCl}$) by the transfer of electrons. Draw its electron-dot structure clearly showing the ions formed.
26.Show the formation of Magnesium chloride ($\text{MgCl}_2$) by the transfer of electrons. Draw its electron-dot structure and explain why two chlorine atoms are required.
27.Show the formation of Magnesium oxide ($\text{MgO}$) and Calcium oxide ($\text{CaO}$) by the transfer of electrons. Draw the electron-dot representation for both.
28.State four general physical properties of ionic (electrovalent) compounds regarding their physical nature, melting/boiling points, solubility, and electrical conductivity.
29.Why do ionic compounds have exceptionally high melting and boiling points? Explain this in terms of electrostatic forces of attraction.
30.Explain why ionic compounds do not conduct electricity in the solid state, but conduct electricity efficiently in the molten state or when dissolved in water.
31.Define the metallurgical terms: (a) Mineral, (b) Ore, (c) Gangue. How is an ore different from a mineral?
32.What is metallurgy? List the three major steps involved in the extraction of metals from their ores to obtain them in a pure state.
33.Explain the term "Enrichment of Ores" (concentration of ores). Name any two physical processes used for this purpose in industry.
34.How are metals of low reactivity extracted? Explain the extraction of mercury from its cinnabar ore ($\text{HgS}$) with balanced chemical equations.
35.Describe how copper is extracted from its sulphide ore copper glance ($\text{Cu}_2\text{S}$) by heating alone in air. Write all balanced chemical equations involved.
36.Metals of medium reactivity are often found as carbonates or sulphides. Differentiate between roasting and calcination with examples and balanced chemical equations.
37.What is reduction in metallurgy? Write the balanced chemical equation for the reduction of zinc oxide ($\text{ZnO}$) using carbon (coke) as a reducing agent.
38.What is the Thermit Reaction? Write its balanced chemical equation. State one important industrial application of this highly exothermic reaction.
39.How are highly reactive metals like sodium, calcium, and aluminium extracted from their ores? Why can they not be reduced by carbon? Explain the electrolysis of molten sodium chloride.
40.Explain the process of electrolytic refining of copper with a neat description of: (a) Anode, (b) Cathode, (c) Electrolyte. Write the chemical reactions occurring at both electrodes.
41.What is anode mud in electrolytic refining? Why does it collect under the anode, and what kind of substances are found in it?
42.Arrange the following steps of extraction in the correct chronological order: Reduction, Refining, Concentration of ore, Roasting/Calcination. Briefly explain why they are ordered this way.
43.What is corrosion? Name three metals that undergo corrosion in moist air, describe the changes in their surface appearance, and write the chemical formula of the corroded product.
44.What are the necessary conditions required for the rusting of iron? Describe an experimental setup using three test tubes to prove these conditions.
45.Define galvanisation. How does coating an iron object with zinc protect it from rusting even if the zinc coating is scratched or broken?
46.Explain how the following methods help in preventing the corrosion of metals:
- Painting, greasing, or oiling
- Tinning and chrome plating
- Alloying
47.What is an alloy? How is it prepared? Write down the metallic constituents, properties, and uses of: (a) Brass, (b) Bronze, (c) Solder.
48.What is an amalgam? What are the constituents of Stainless Steel? Explain why stainless steel is preferred over pure iron for making household utensils and surgical instruments.
A railway welder, Rohit, needs to join two broken tracks on a remote railway line. He mixes iron(III) oxide powder with aluminium powder in a crucible, places it over the gap, and ignites the mixture using a magnesium ribbon. A violent reaction occurs, and liquid iron flows into the gap, welding the tracks together.
49.Based on Case Study 1, answer the following:
- Write the balanced chemical equation for the reaction that occurred. Identify the oxidizing and reducing agents.
- Why does the iron obtained in this reaction exist in a molten (liquid) state?
- Why is aluminium used instead of carbon as a reducing agent in this reaction?
An industrial copper refinery uses electrorefining to purify crude copper containing impurities like zinc, iron, gold, silver, and platinum. A large current is passed through an acidic copper sulphate bath using electrodes of crude and pure copper.
50.Based on Case Study 2, answer the following:
- Which electrode (crude copper or pure copper) is made the anode and which is made the cathode? Explain why.
- Describe what happens to the impurities: (a) Zinc and iron, (b) Gold and silver.
- Write the balanced ionic equations for the reactions occurring at the anode and the cathode.
A plumber is installing water pipes in a house. He has a choice between plain iron pipes, galvanised iron pipes, and copper pipes. He chooses galvanised iron pipes for the main water supply and copper pipes for hot water lines.
51.Based on Case Study 3, answer the following:
- Why are plain iron pipes not suitable for drinking water supply lines?
- Explain the concept of cathodic/sacrificial protection shown by the galvanised pipes.
- Why are copper pipes preferred over galvanised iron pipes for hot water supply? Explain based on reactivity.
An old goldsmith was approached by a customer wanting to clean a tarnished gold crown. The goldsmith dipped the crown in a freshly prepared yellow, highly corrosive liquid. The crown sparkled brilliantly, but when weighed later, its mass had decreased slightly. The customer accused the goldsmith of theft.
52.Based on Case Study 4, answer the following:
- What is the chemical name of the liquid used by the goldsmith? What is its chemical composition?
- Explain why the mass of the gold crown decreased after dipping it in the liquid. Write the chemical basis.
- Is gold reactive towards oxygen, water, or dilute acids? Why is it called a noble metal?
In a chemistry lab, a student tries to extract sodium metal by electrolysing an aqueous solution of sodium chloride (brine). She expects sodium to deposit at the cathode, but instead, she observes hydrogen gas bubbles at the cathode and chlorine at the anode. Her teacher explains that she must use molten sodium chloride instead of aqueous solution.
53.Based on Case Study 5, answer the following:
- Why was hydrogen gas evolved at the cathode instead of sodium metal during the electrolysis of aqueous NaCl? Explain in terms of reactivity.
- Write the chemical equations for the reactions occurring at the anode and cathode during the electrolysis of molten NaCl.
- Why must highly reactive metals like sodium only be extracted by electrolytic reduction of their molten halides?
Four metals A, B, C, and D were added to the following solutions one by one. The observations recorded are given in the table below:
| Metal |
Iron(II) sulphate |
Copper(II) sulphate |
Zinc sulphate |
Silver nitrate |
| A |
No reaction |
Displacement |
— |
— |
| B |
Displacement |
— |
No reaction |
— |
| C |
No reaction |
No reaction |
No reaction |
Displacement |
| D |
No reaction |
No reaction |
No reaction |
No reaction |
54.Based on the Reactivity Series Challenge table, answer the following:
- Which is the most reactive metal? Justify your answer.
- What would you observe if metal B is added to a solution of Copper(II) sulphate? Explain.
- Arrange the metals A, B, C, and D in the order of decreasing reactivity.
A greyish-silver metal 'X' is widely used in making roofing sheets and protective coatings. When 'X' is heated strongly in air, it forms a white powder 'Y'. White powder 'Y' dissolves in both dilute hydrochloric acid and sodium hydroxide solution. When metal 'X' is treated with steam, it evolves a highly flammable gas 'Z' and leaves a residue of 'Y'.
55.Based on the description of the Mystery Metal, answer the following:
- Identify metal 'X', white powder 'Y', and gas 'Z'.
- Write balanced chemical equations for: (a) Reaction of 'X' with oxygen, (b) Reaction of 'Y' with hydrochloric acid, (c) Reaction of 'Y' with sodium hydroxide.
- Write the balanced equation for the reaction of 'X' with steam.
56.Explain why aluminium sheets are widely used to wrap food and pharmaceutical items even though aluminium is a highly reactive metal. Explain the role of the protective oxide layer (anodising).
57.Why do copper vessels get covered with a green coating when exposed to moist air for a long time? Write the name and chemical formula of the green coating, and write the chemical equation involved.
58.A metal 'M' is found in nature in the form of its carbonate ore $\text{MCO}_3$. Outline the metallurgical steps required to obtain the pure metal 'M' from this ore. Write the chemical equations involved.
59.Why is pure gold (24 carat) not suitable for making jewellery? How is it made hard enough for jewellery making? What is 22 carat gold?
60.Contrast the electrical conductivity of graphite and diamond, explaining the difference in terms of carbon bonding. Why is graphite used as electrodes?
61.What chemical reaction takes place when iron filings are heated strongly in air? Write the balanced chemical equation and state the name of the product formed.
62.Write the electron-dot structures for: (a) Oxygen molecule ($\text{O}_2$), (b) Nitrogen molecule ($\text{N}_2$), showing the shared pairs of electrons.
63.Explain why non-metals do not displace hydrogen gas when treated with dilute acids. Explain in terms of electron transfer.
64.An ionic compound 'X' is highly soluble in water and conducts electricity in solution. However, it is highly brittle and breaks when struck with a hammer. Explain these physical observations.
65.An old iron bridge is being demolished. A student notices that some parts are coated with red rust, some are coated with grey zinc paint, and some bolts are made of brass. Using your chemical knowledge of corrosion, evaluate the effectiveness and long-term durability of these three anti-corrosion methods.
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