Ans: Metals are the elements which form positive ions by losing electrons.
2. What is meant by non-metal?
Ans: Non-metals are the elements which form negative ions by gaining electrons.
3. Define metals.
Ans: Metals are those electropositive elements which are good conductor of heat and electricity. For example, gold, platinum, iron, etc.
4. Define non-metals.
Ans: Non-metals are those electropositive elements which are bad conductor of heat and electricity.
For example, oxygen, nitrogen, sulphur, iodine, etc.
5. Write any three physical properties of metals.
Ans: The physical properties of metals are:
• Metals are good conductor of heat and electricity.
• They are ductile in nature.
• They can be converted into thin sheet after hammering. Thus, we can say that they are malleable in nature.
6. What is ductility?
Ans: The property of metal being made into wires is called ductility.
7. What is an alloy? Write with example.
Ans: An alloy is defined as a homogeneous mixture of two or more metals and non-metals. For example, brass is an alloy of copper and zinc.
8. Write any two properties of Alloy.
Ans: Properties of alloy are:
• They have low melting point.
• They are good conductors of heat and electricity.
9. What are metalloids? Give any two examples of metalloids.
Ans: The elements that show the properties of both metals and non-metals are called metalloids.
Examples of metalloids are arsenic and germanium.
10. What is metallic clink?
Ans: Metals, when struck with a hammer emit a peculiar sound called metallic clink.
11. How are metal different from non-metal?
Ans: Metals are those elements which can conduct heat and electricity but non-metals are bad conductors of heat and electricity.
12. Define malleability.
Ans: The property of metals to be beaten into a thin plate is called malleability.
13. Name any two metals that are harmful to human.
Ans: Two metals that are harmful to human are:
• Lead
• Mercury
14. Define metallic bond.
Ans: The force of attraction that occurs between the free electrons and positive metallic ions without any chemical reaction for holding metal atoms together is called metallic bond.
15. Differentiate between:
Metals and non-metals
Ans: | Metals | Non Metals |
| Metals are solid at normal temperature except for mercury. | Non-metals can be found in all three states. |
| They have high melting and boiling point. | They have low melting and boiling point. |
| They possess luster. | They do not possess luster. |
| They are good conductor of heat and electricity. | They are bad conductor of heat and electricity. |
| They are malleable and ductile. | They are not malleable and ductile. |
16. Differentiate between:
Metals and Metalloids.
Ans: | Metals | Metalloids |
| They are good conductor of heat and electricity. | They are poor conductor of heat and electricity. |
| They are malleable and ductile. | They are not malleable and ductile. |
17. Metals are malleable and ductile. Explain on the basis of electron sea model.
Ans: According to the electron sea model, the bonds between metal ions and mobile free electrons are non directional. Due to this the attraction between positive metal ions and free electrons is uniform in all directions. Hence, when external force is applied on metals, the positive metallic ions slide from one side to another. Thus, the metal is deformed to a sheet or a wire without destroying the structure of the metal crystal. This ability makes a metal malleable and ductile.
18. Graphite and iodine are non metals. Still they shine, Explain it with suitable reason.
Ans: Graphite and iodine are non metals, still they shine because going down the group the size of the atom increases because of shielding effect due to which the interaction between the atom and the outermost electron decreases so these electrons on the surface of iodine become excited by absorbing heat energy from light so when they release this energy and come to their normal state, they emit this light so it appears that they have lustrous surface.
19. Write the chemical properties of metals with an example of each.
Ans: Chemical properties of metals
• Metals react with oxygen to form basic oxides.
2Na + O2 → 2NaO
• Metals form salt and gas when reacting with acids.
Zn + 2HCl → ZnCl2 + H2
• When hydrogen is passed through metals like copper, sodium potassium hydride is formed.
Ca +H2 → CaH2
20. Write the chemical properties of non metals.
Ans: Chemical properties of non-metals
• They form stable hydrides with oxygen.
• They give acidic oxides.
• They are liberated at the anode during the electrolysis.
21. What is the melting and boiling point of silver?
Ans: The melting point and boiling point of silver are 960°C and 1955°C respectively.
22. Write any three points to show the importance of each:
a) Zinc
b) Sodium
c) Potassium
Ans: a) Zinc b) Sodium
c) Potassium
• Zinc plays a role in cell division, cell growth and wound healing.
• It helps in maintaining sufficient immune system of the body against various diseases.
• It helps in normal growth and development of infancy during pregnancy, childhood and adolescence.
b) Sodium
• The different concentrations of Na+ ions produce an electrical potential across the membrane, which helps the functioning of the nerve and the muscle.
• Sodium helps to regulate fluids in the body.
• Sodium helps in muscle contraction.
c) Potassium
• The different concentrations of K+ ions produce an electrical potential across the membrane, which helps the functioning of the nerve and the muscle.
• Potassium ions inside the cell are important for metabolism of glucose, synthesis of proteins and activation of some enzymes.
• Potassium ions are also important in maintaining blood pressure and heart functioning properly.
23. Write any three harmful effects of:
a) Lead
b) Mercury
Ans: a) Leadb) Mercury
• Lead can affect almost every organ and system in the human body.
• Ingestion of lead can cause seizures, coma and even death.
• It decreases the transportation of oxygen and calcium.
b) Mercury
• It causes serious impact on the developing nervous system, liver, lungs, kidneys, immune and reproductive systems.
• It causes high blood pressure, alters heart beat rate and increases the heart attack.
• It causes impairment of speech, hearing, walking, behavior memory, mental retardation, learning disabilities, etc.
24. Write in brief about micronutrients and macronutrients with examples.
Ans: Micronutrients, as opposed to macronutrients (protein, carbohydrates and fat), are comprised of vitamins and minerals which are required in small quantities to ensure normal metabolism, growth and physical well‐being. For examples, vitamins, minerals.
Nutrients are environmental substances used for energy, growth, and bodily functions by organisms. Depending on the nutrient, these substances are needed in small amounts or larger amounts. Those that are needed in large amounts are called macronutrients. For examples, carbohydrates, fats, proteins.
25. Give reasons:
Ionic compounds have high melting points.
Ans: Ionic compounds have high melting points because the electrostatic interactions that hold the compounds together are very strong.26. Give reasons:
Metals are lustrous.
Ans: Metals are lustrous due to oscillation of electrons on surface of metal.27. Give reasons:
Metals are ductile.
Ans: Metals are made up of positive metal ions surrounded by electrons. The metal ions can easily slide past one another as they “float” in the electron. This allows the metal to be pounded into thin sheets or stretched into wires without breaking the metallic bonds. So metals are ductile.28. Give reasons:
Lead is harmful for humans.
Ans: Lead is harmful for humans because the consumption of lead affects various organ and system in the body, retards the development of the body.29. Give reasons:
Metals are good conductors of electricity.
Ans: Metals are good conductors of electricity, because they have free electrons. These free electrons act as charge carriers in the metallic structure, allowing electric current to flow through the metal.30. Give reasons:
Metals are used for making cooking appliances.
Ans: Since metals are good conductors of heat, the food can be cooked fast due to which they are used to make cooking utensils.
31. Give reasons:
Electroplating of copper can be made on iron but not in silver.
Ans: Copper can be electroplated on iron because iron is more reactive than copper. Since silver is less reactive than copper. That is silver lie below copper in electrochemical series. Copper cannot be electroplated onto silver.
32. What are reactive metals?
Ans: Metals which readily take part in chemical reaction; the metal which lie above the position of hydrogen in electrochemical series.
For example sodium, potassium, calcium magnesium etc.
33. What are less reactive metals?
Ans: The metals which lie below the position of hydrogen in electrochemical series are less reactive metals.
For example copper, mercury, silver, gold etc.
34. What is electrochemical series?
Ans: When the electrodes (metals and non-metals) in contact with their ions are arranged on the basis of the values of their standard reduction potentials or standard oxidation potentials, the resulting series is called the electrochemical or electromotive or activity series of the elements.
Electrochemical series
| Element | Electrode Reaction (Reduction) |
| Li | Li+ + e- → Li |
| K | K+ + e- → K |
| Ca | Ca2+ + 2e- → Ca |
| Na | Na+ + e- → Na |
| Mg | Mg2+ + 2e- → Mg |
| Al | Al3+ + 3e- → Al |
| Zn | Zn2+ + 2e- → Zn |
| Cr | Cr3+ + 3e- → Cr |
| Fe | Fe2+ + 2e- → Fe |
| Cd | Cd2+ + 2e- → Cd |
| Ni | Ni2+ + 2e- → Ni |
| Sn | Sn2+ + 2e- → Sn |
| H2 | 2H+ + 2e- → H2 |
| Cu | Cu2+ + 2e- → Cu |
| I2 | I2 + 2e- → 2I- |
| Ag | Ag+ + e- → Ag |
| Hg | Hg2+ + 2e- → Hg |
| Br2 | Br2 + 2e- → 2Br- |
| Cl2 | Cl2 + 2e- → 2Cl- |
| Au | Au3+ + 3e- → Au |
| F2 | F2 + 2e- → 2F- |
35. Write the characteristics of metalloids.
Ans: Elements having both properties of metal and non metals are called metalloids.
Characteristics are:
• They are neither malleable nor ductile.
• They possess metallic luster.
• They are poor conductor of heat and electricity.
• They combine with hydrogen to form hydrides.
36. Differentiate between macro and micro nutrients.
Ans: The differentiate between macro and micro nutrients are:
| Macronutrients | Micronutrients |
| Required in large quantity. | Required in small amount. |
| For examples, carbohydrate, fat. | For examples, vitamins, minerals. |
37. Define electron sea model.
Ans: A model of metallic bonding in which the atoms are surrounded by an electron cloud or sea and are considered to be fixed points within a mobile ‘sea’ of electrons is called electron sea model.
38. How do metals conduct heat and electricity?
Ans: When one end of metal is heated, the free electrons present in that region absorb heat and acquire large kinetic energy. Hence, according to the electron sea model, the valence or free electrons of metal become mobile and move from the heated end to another end. Thus, the heat gets conducted.
According to the electron sea model, valence electrons are not bound to any particular metallic nucleus but they are highly mobile as free electrons in metals. When an electric current is applied into an end of the metallic conductor, the free electrons start moving from that to another end. In this way, electricity is conducted through metals.
39. Why are metals malleable and ductile?
Ans: According to electron sea model, the bonds between metal ions and mobile free electrons are non directional. Due to this the attraction between positive metal ions and free electrons is uniform in all directions. Hence, when external force is applied on metals, the positive metallic ions slide from one side to another. Thus, the metal is deformed to a sheet or a wire without destroying the structure of the metal crystal. This ability makes a metal malleable and ductile.
40. Metals are highly electropositive in nature, why?
Ans: Metals are highly electropositive in nature because most of the metals lose electrons from their valence shell due to weak force of attraction on the outermost shell.
41. Differentiate between malleability and ductility.
Ans: The differences between malleability and ductility are:-
| Malleability | Ductility |
| It is the capacity of a material to withstand deformation under compression without rupture. | It is the ability of a material to undergo deformation. |
| Property of material by virtue of which it can be drawn into thin sheets. | Property of material by virtue of which it can be drawn into wires. |
| It is a compressive property. | It is a tensile property. |
| Examples – gold, silver, aluminium etc. | Examples- mild steel, copper, zinc etc. |
42. Why are metals hard and less brittle than others?
Ans: Metals hard and less brittle than others because their molecules are closely packed except in lithium, sodium and potassium.
43. Why are sodium and potassium metals stored in kerosene?
Ans: Sodium and potassium highly reactive metals so they are stored in kerosene as they can easily catch fire even when they come in contact with air.
44. What is electrolyte?
Ans: A compound that conducts electric current when dissolved in water or in molten state is called electrolyte.
45. Name liquid non-metal.
Ans: Bromine is liquid non metal.
46. What are minerals? Write the name of any three minerals with their chemical composition.
Ans: A mineral is an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes.
Examples-
• Gypsum-CaSO4.2H2O
• Calcite-CaCO3
• Fluorite-CaF2
47. What happens when:
Non-metals are heated with oxygen?
Ans: Non metals form acidic oxides when heated with oxygen.C + O2 → CO2
48. What happens when:
Metals react with sulphur?
Ans: Metals form sulphide when heated with sulphur.Fe + S → FeS
49. What happens when:
Metals react with halides?
Ans: Metals react with halogens to form salts.2Na + Cl2 → 2NaCl
50. What happens when:
Metals react with oxygen?
Ans: Metals react with oxygen to form basic oxides.4Na + O2 → 2Na2O
51. What is ore?
Ans: Ore is naturally occurring mineral or aggregate of minerals from which economically important constituents, especially metals can be extracted.
52. Which metal is obtained from magnetite?
Ans: Iron is obtained from magnetite.
53. What metal is obtained from bauxite?
Ans: Aluminium is obtained from bauxite.
54. Name the important alloys with their composition and uses.
Ans:
| Name | Composition | Use |
| Brass | Cu (60 to 80%), Zn (40 to 20%) | For making household utensils |
| Bronze | Cu (75 to 90%), Sn (25 to 10%) | For making coins, idols, utensils |
| German Silver | Cu (60%), Zn (25%), Ni (15%) | For making utensils |
| Magnelium | Mg (5%), Al (95%) | For making aircraft frame |
| Rolled Gold | Cu (90%), Ni (10%) | For making cheap ornaments |
| Monel metal | Cu (70%), Ni (30%) | For making alkali resistant containers |
| Bell metal | Cu (80%), Sn (20%) | For making bells |
| Gun metal | Cu (85%), Zn (10%), Sn (5%) | Used for engineering purposes |
| Solder | Sn (50-75%), Pb (50-25%) | Soldering of metals |
| Duralium | Al (95%), Cu (4%), Mg (0.5%), Mn (0.5%) | In aircraft manufacturing |
| Steel | Fe (98%), C (2%) | For making nails, screws, bridges |
| Stainless Steel | Fe (82%) Cr, Ni (18%) | For making cooking utensils, knives |
55. What do mean by minerals?
Ans: The natural materials in which the metals or their compounds are found in the earth are called minerals.
56. What do you mean by magnetic separation?
Ans: The process in which the magnetic ores are attracted by a magnet and their impurities which are left are deposited at a separate place is known as magnetic separation.
57. What is calcination?
Ans: The process of conversion of carbonate, hydrated oxide or hydroxide ores to their respective oxides by heating the ore, either in the absence of air or in the limited supply of air is called calcination.
58. What is an ore?
Ans: An ore is defined as a mineral from which the metal can be profitably extracted.
59. What do you mean by the concentration of ore?
Ans: The removal of gangue from an ore is called concentration of ore.
60. What is gangue?
Ans: The waste material or impurity associated with an ore is called gangue.
61. What are amalgams?
Ans: The alloys of the metals with mercury are called amalgams.
62. What is meant by metal?
Ans: Metals are the elements which form positive ions by losing electrons.
63. What is meant by non-metal?
Ans: Non-metals are the elements which form negative ions by gaining electrons.
64. Why are metals used to make cooking utensils?
Ans: Metals are used in making cooking utensils because they are good conductor of heat and electricity.
65. Why the melting and boiling points of copper is higher than that of sodium?
Ans: It is because copper is hard metal with high density and sodium is soft metal with low density.
66. What is metallurgy?
Ans: The process of obtaining metal from its ore is known as metallurgy.
67. What is rusting?
Ans: The formation of red or brown scales or powder on the surface of iron when it comes in contact with moist air is called rusting.
68. What is roasting?
Ans: The process of conversion of the ore into metallic oxide by heating it in an excess of air at temperatures insufficient to melt the ore is called roasting.
69. What is hydrolysis?
Ans: Hydrolysis is a chemical process involving the breaking of a bond in a molecule by the addition of water.
70. A moist iron piece left in the air becomes reddish brown. Why?
Ans: It is because a moist iron reacts with oxygen present in the air to form hydrated iron oxide which is reddish brown in colour called rust.