Metals and Nonmetals PDF

## Metals & Non-Metals ### Introduction All the elements can be classified as either metals or non-metals depending on their properties. If we call one element as metal, it will show some definite set of properties and if we call some other element as non-metal, it will show some other definite se...

## Metals & Non-Metals ### Introduction All the elements can be classified as either metals or non-metals depending on their properties. If we call one element as metal, it will show some definite set of properties and if we call some other element as non-metal, it will show some other definite set of properties. So, now we will discuss general characteristics of metals and non-metals, and their uses. ### Characteristics of Metals and Non-Metals Out of the 92 naturally occurring elements, about 70 are identified as metal and about 22 as non-metals. Copper, Iron, Zinc, Aluminium, Gold, Silver, Tungsten etc. display the properties of metals, like they produce ringing sound when struck on hard surfaces. They are good conductors of heat and electricity. Chlorine, Bromine, Helium, Oxygen, Carbon are known as non-metals. Bromine is liquid, while iodine are soft solids at room temperature. They melt at low temperature, break easily when hammered and are bad conductors of heat and electricity. Non-metals normally display properties opposite to that of metals. ### Exercise 1 Fill in the blanks: (i) Metals produce **sound** when struck on a hard surface. (ii) Non-metals are **bad** conductors of heat. (iii) Iron is example of **metal** and chlorine is of **non-metal.** ### Occurrence All materials found in the earth are composed of chemical elements. At present 118 elements are known but all of them do not occur in nature. With an exception of few elements from hydrogen to uranium are naturally occurring. Out of naturally occurring elements only 10 elements make up about 99% of mass of earth crust. The first three most abundant elements in the earth's crust are (i) Oxygen (ii) Silicon (iii) Aluminium The most abundant elements in the universe are (i) Hydrogen (ii) Helium ### Refining of Metals The metals obtained through above reduction processes are not very pure. They contain impurities, so they must be purified to obtain pure metals. The process of purification is based on the nature of the metal and the nature of impurity. ### Illustration 1 Write difference between Calcination and Roasting. Calcination is the process in which a carbonate ore is heated strongly, in the absence of air, to convert it into metal oxide. $ZnCO_3(s)\longrightarrow ZnO(s)+ CO_2$ Roasting is the process in which a sulphide ore is strongly heated, in the presence of air, to convert it into metal oxide. $2ZnS(s) + 3O_2(g) \longrightarrow 2ZnO(s)+ 2SO_2(g)$ ### Exercise 2 Name the metals and non-metals which occur in free state? ### Physical Properties Metals and Non-metals All the metals and non-metals have some of these characteristic properties. ### Physical State Metals have a definite shape in normal conditions. Metals are solids at room temperature and have high melting points. Mercury is the only exception; as this is the only metal which exists as liquid at room temperature. Non-metals can be solid state, liquid or gas at room temperature. Nitrogen, Oxygen etc. exist in gaseous state at room temperature. Carbon, Phosphorous etc. are solid at room temperature. Bromine is liquid at room temperature. The boiling point and melting point of non-metals are less as compared to metals. Majority of non-metals are gases at room temperature. Metals are generally solid at room temperature. Mercury is a metal which is liquid at room temperature. Gallium and cesium have melting point just above room temperature. They can melt in our palm. ### Lustre Metals are very shiny and have metallic lustre, which make them useful for jewellery purpose. On the other hand, non-metals have wide variety of colour range, but have very dull lustre. lodine is a non-metal which has lustre. Graphite is a form of carbon which has lustre. ### Malleability The property of beating a metal into thin sheets is called malleability. Non-metals are not malleable. Gold is the most malleable metal. ### Ductility Ductility is the property that allows the substance to be drawn into wires. Metals have this property. This is the reason why we are able to see the wires of Copper, Aluminium and Iron. Non-metals are not ductile in nature. We can not draw wires from non-metals. ### Conductivity Metals are good conductors of heat and electricity. Silver is best conductor followed by copper, Gold and aluminium. Non-metals are insulators and in general they are supposed to be bad conductors of electricity. Mercury is a metal which is a poor conductor of heat. ### Hardness It is difficult to cut metals and they are also able to bear a heavy load over them. Metals are hard. Non-metals are brittle, i.e., they break on heating. Although Sodium and Potassium (Metals) are so soft that they can be cut with knife, while diamond is the hardest substance (a form of Carbon). So, in general we can say that an element can be easily identified as metal or non-metal by comparing its properties of metals and non-metals. But sometimes, some elements do not fall in any category. Then are known as, semi-metals or metalloids. ### Exercise 3 Name, whether this property is shown by metal or non-metal: (i) Hardness - **Metal** (ii) Bad conductance of heat - **Non-metal** (iii) Ductility - **Metal** (iv) Malleability - **Metal** (v) Lustre - **Metal** ### The Reactivity Series of Metals (Or Activity Series of Metals) Some metals are chemically very reactive, whereas others are less reactive or unreactive. For example, Potassium and Sodium react very, very rapidly with cold water. So, they are very reactive metals. Zinc and iron react only with steam. So, they are less reactive metals. On the other hand, copper and silver do not react even with steam. So, they are quite unreactive metals. On the basis of vigour of reactions of various metals with oxygen, water and acids, as well as displacement reactions, the metals have been arranged in a group or series according to their chemical reactivity. The arrangement of metals, in a vertical column in the order of decreasing reactivities, is called reactivity series of metals (or activity series of metals). In reactivity series, the most reactive metal is placed at the top; whereas, the least reactive metal is placed at the bottom. The reactivity series of the common metals is given below: ### Exercise 4: Name the metal which occurs in free state? ### Chemical Properties of Metals & Non-Metals Metals and non-metals show different behaviour towards different chemicals. ### Reaction with Oxygen In general, metals react with oxygen to form oxides. Na, K burn in air. They are stored in kerosene. Aqueous solutions of these oxides are alkaline or basic in nature, $2Mg(s) + O_2(g) \longrightarrow 2MgO; MgO+ H_2O \longrightarrow Mg(OH)_2$ This Mg(OH)2 solution changes red litmus into blue, indicating that the solution is alkaline. Similarly, non-metals react with oxygen to form their oxides, but on adding small amount of water to these oxides, solution becomes acidic. $S + O_2 \longrightarrow SO_2; SO_2+ H_2O \longrightarrow H_2SO_3$ The solution of H2SO3 turns blue litmus paper into red. This change indicates that the solution is acidic in nature. Therefore, for differentiating metals from non-metals, we can say that oxides of metals are basic in nature and oxides of non-metals are acidic in nature. ### Reaction with Water Different metals react with water at different rates. Sodium reacts violently with water to form sodium hydroxide and hydrogen gas is liberated in the process. $2Na + 2H_2O \longrightarrow 2NaOH + H_2$ Magnesium virtually has no reaction with cold water, but reacts vigorously with hot water. $Mg+2H_2O \longrightarrow Mg(OH)_2 +H_2$ Similarly, Zinc and Iron react very mildly with steam; whereas Copper, Silver and Nickel do not react with water. Non-metals do not react with water. Some of the non-metals like Phosphorus is kept in water, so that its contact from air can be avoided; ### Reaction with Acids Aluminium, Iron and Copper when react with dilute hydrochloric acid, Aluminium and Iron form AlCl3 and FeCl2, and H2 gas is evolved in each case, but copper does not react with dil HCl. But, it reacts with Conc. Sulphuric Acid and Nitric Acid. $2AI+6HCI \longrightarrow 2AICI_3 + 3H_2$ $Fe + 2HCI\longrightarrow FeCI_2 + H_2$ Normally, non-meals do not react with acids, although Sulphur reacts with hot concentrated Nitric Acid. $S+4HNO_3 \longrightarrow SO_2 + 4NO_2 + 2H_2O$ ### Illustration 2: Write the balanced chemical reaction for the following: Burning of sulphur. $S + O_2 \longrightarrow SO_2$ ### Exercise 4 Reaction between sulphur and hot conc. nitric acid. ### Exercise 5 (i) True (ii) False (iii) False ### Metal Replaces Metal A metal more reactive metal displaces the less reactive metal; like Mg replaces copper from CuSO4 solution. $Fe + CuSO_4\longrightarrow FeSO_4 + Cu$ $Mg+CuSO_4\longrightarrow MgSO_4 + Cu$ $Zn + CuSO_4\longrightarrow ZnSO_4 + Cu$ ### Noble Metals Metals which have very less tendency to react and can be found in free state in nature, are known as noble metals. Example: Gold and Platinum. They have the property to maintain their metallic lustre for a long time. Gold remains unaffected by air, water and also acidic and basic substances. Gold is soft, extremely ductile and malleable. It dissolves only in aqua regia. (A mixture of conc. HNO3 and conc. HCI in the ratio 1:3 by volume.) ### Illustration 3 What is the use of Sulphur? It is a major constituent of important industrial chemicals. ### Exercise 6 Write the uses of gold. Write the uses of iron. ### Common Alloys Most of the metals are not useful in its purest form, i.e; a 100% pure metal can not be used in daily life. For making the metals useful for various purposes, we have to add some other metals or non-metals which will result in desirable properties. Such a mixture is called an alloy. So, alloy is a homogeneous mixture of a metal with another metals or non-metals. ### Exercise 7 (i) What are the constituents of steel? (ii) What are the constituents of bronze? ### Corrosion Rusting of Iron objects, which we see in our daily life, get rusted some time because of exposure to atmosphere. This rusted layer surface of the objected is called corrosion. Corrosion, in case of iron, is called "rusting". We can easily remove rust from the surface of the iron. This wasting away of metal layer and can be cleaned very easily. Most of the iron objects get corroded as iron is widely used metal and plays an important role in national economy, rusting is of great concern. We need to stop it and this is the two essential component in our daily life. We can keep the iron objects safe from moist air then we can prevent them from rusting. There are several ways of doing that. (a) Painting: We coat different objects of iron and steel by paint so as to protect them from rusting. (b) Greasing: Brand new tools, scissors and knives are coated with oil or grease. (c) Galvanization: Some times surface of iron is coated with a layer of zinc (non corrosive metal) and this process is called galvanization. (d) Electroplating: Iron, at times, is coated with a thin layer of tin of chromium metals which is resistant to corrosion. This is done by electroplating. Tin surface makes the container safe for storing food. Chromium layer not only works as corrosion preventive layer, but also gives a good shining appearance. (e) Alloying: Some metals when alloyed with other, they become resistant to corrosion. Example: stainless steel. ### Illustration 6 Define the term corrosion? The wasting away of metal layer due to the formation of metal compounds on the surface, is called corrosion. ### Exercise 8 What is electroplating? ### Solved Problems Subject - A 1. Complete the reactions: #(a) Zn + CuSO4 → ZnSO4 + Cu #(b) S + HNO3 → SO2 & NO2 + H2O #(c) Mg + H2O(steam) → MgO + H2 #(d) Al + AgNO3 → Al(NO3)3 + Ag 2. Give two uses of zinc. #(a) It is used in galvanizing iron. #(b) Making container of dry cells. 3. Give two uses of silicon. #(a) Making solar cells, microchips and transistors. #(b) Used in the manufacture of silicon carbide (semiconductor). 4. List the different uses of metals that you come across in everyday life. #(a) Machinery #(b) Automobiles, Aeroplanes, trains etc #(c) Cooking, utensils, electrical gadgets. #(d) Electrical wires #(e) Thin sheets 5. What happens when #(a) Magnesium reacts with concentrated sulphuric acid #(b) Zinc reacts with concentrated nitric acid #(a) Mg + H2SO4(Conc) → MgSO4 + SO2 + H2O #(b) Zn + HNO3(Conc) → Zn(NO3)2 + NO2 + H2O ## Assignment ### Section A Very Short Answer Type Questions 1. Name the gas which has less tendency to react and is found in free state in nature. **Answer**: Noble gases. 2. Why does gold and silver occur in native state? **Answer**: Gold and silver possess negligible or very less reactivity. 3. (i) Unwanted material with ore is called ……….. (ii) Metal combines with oxygen to form ………. oxides. **Answer**: (i) Gangue (ii) Basic. 4. Name the metal which is kept in kerosene to prevent their reaction with water. **Answer**: Potassium and sodium. 5. Compare the nature of oxides in metals, non-metals. **Answer**: Metallic oxides are basic in nature and non-metallic oxides are acidic in nature. 6. Name a metal which displaces copper from copper sulphate solution. **Answer**: Zinc. 7. Name two metals which are solid at room temperature and melt in the palm of our hand. **Answer**: Gallium, Caesium. ### Section B Short Answer Type Questions 1. Explain the term metallurgy. **Answer**: Metallurgy is the science of extracting metal from their ores profitably and purifying them. 2. Name the metal which occurs in free state. **Answer**: Gold, Silver. 3. Why is tincture iodine used to protect wound from germs? **Answer**: Iodine is a non-metal. 4. Compare the physical properties of non-metals and metals with respect to (a) malleability (b) ductility (c) conductivity **Answer**: Metals are generally malleable, ductile and good conductor of heat and electricity whereas non-metals are brittle and poor conductors of heat and electricity. 5. Taking example of magnesium and sulphur, explain how non-metals produce oxides with different characteristics. **Answer**: Magnesium reacts with oxygen to form magnesium oxide, which is basic. Sulphur reacts with oxygen to form sulphur dioxide which is acidic in nature. 6. Which of the following will form acidic oxide: P, H, Na, Ca? **Answer**: P and H. 7. Which metal is the poorest conductor of heat & electricity? **Answer**: Mercury. 8. Write the constituents of stainless steel. **Answer**: Iron, Chromium and Nickel. 9. Solder is an alloy of which elements? **Answer**: Tin and lead. 10. Which is the best conductor of electricity? **Answer**: Silver. ### Section C Long Answer Type Questions 1. Give different uses of metals in daily life. **Answer**: Metals are used in daily life in many ways. Some of the major uses are: * **Machinery:** Used for making heavy machinery, tools, industrial equipment, etc. * **Construction:** Used in buildings, bridges, roads, and other infrastructure. * **Transportation:** Used for making automobiles, trains, airplanes, ships, etc. * **Electrical:** Used for making wires, electrical gadgets, and other electronics. * **Utensils:** Used for making pots, pans, cutlery, and other kitchen equipment. * **Jewelry and decoration:** Used in making ornaments, statues, and other decorative items. * **Packaging:** Used for making cans, foils, and other packaging materials. * **Other applications:** Metal is used in a wide range of other applications, such as in medicine, agriculture, and aerospace. 2. What are the constituents of: (a) Steel (b) Stainless steel. (c) Bronze (d) Brass **Answer**: (a) **Steel:** Iron with a small percentage of carbon. (b) **Stainless steel:** Iron with larger amounts of chromium and nickel, which makes it resistant to rust. (c) **Bronze:** Copper, Tin. (d) **Brass:** Copper, Zinc. 3. Give reasons for the following: (a) Iron is used for constricting bridges and houses. (b) Iron sheets are galvanized before use. (c) Graphite is used as an electrode in a dry cell. **Answer**: (a) **Iron** is a strong and durable metal that can be used in a wide variety of construction applications, including bridges and houses. * It is versatile and can be easily shaped into different forms. * It is relatively inexpensive compared to other construction materials. (b) **Iron sheets are galvanized before use** because it makes it resistant to rusting, increasing its lifespan and durability. The process of galvanization involves coating the iron sheet with a thin layer of zinc. Zinc is more reactive than iron, so it will corrode first, protecting the iron from rusting. (c) **Graphite is used as an electrode in a dry cell** because it is an excellent conductor of electricity. This enables the flow of electricity through the cell and makes its operation possible.. * It is resistant to chemical attack by the electrolyte solution in the cell. 4. What is metallurgy? Explain different processes involved in metallurgy. **Answer**: Metallurgy is the science and technology of extracting metals from their ores and refining them. There are several steps in metallurgy, and these steps may vary depending on the metal: * **Mining:** The first step is retrieving the raw ore from the earth's crust. This involves a variety of techniques and methods, depending on the nature of the ore and its location. * **Crushing and Grinding:** Once the ore is mined, it needs to be crushed and ground into smaller particles to make it easier to process. * **Concentration:** The next step is concentrating the ore, which aims to remove impurities and unwanted materials. This can be achieved using various methods, such as: * **Froth flotation:** Utilizing the properties of minerals, this process concentrates valuable minerals by separating them from impurities. * **Magnetic separation:** Using magnets to separate magnetic minerals from non-magnetic ones. * **Gravity separation:** Using the difference in density between the mineral and the impurities to separate them. * **Conversion to Metal Oxide:** The next step is to convert the concentrated ore into metal oxide. This is done using methods like: * **Roasting:** This process involves heating the ore in the presence of air to remove sulfur and other impurities, leaving behind the metal oxide. * **Calcination:** Similar to roasting, but involves heating without air to decompose the ore and drive off carbon dioxide leaving the metal oxide. * **Reduction:** The metal oxide is then reduced to the pure metal. Reduction is a chemical reaction in which an element or compound loses oxygen. The process can be achieved using different reducing agents such as carbon, hydrogen, or magnesium. * **Carbon reduction:** Carbon is a common reducing agent, particularly for iron. * **Electrolysis:** This is used for metals that are more reactive than carbon, separating the metal from its ore using an electric current. * **Refining:** The final step is refining the metal to remove any remaining impurities and produce a pure metal. Refining methods include: * **Electrolytic refining:** Using an electric current, metals are refined by depositing pure metal on a cathode from an impure metal anode. * **Zone refining:** This process is used to purify silicon and germanium, where the molten metal is slowly passed through a zone heated with an electrical heater. * **Vacuum refining:** Involves heating impure metal under vacuum to remove impurities. 5. (a) Hardness (b) Lustre (c) Tensile strength Compare the following physical properties of metals and non-metals. **Answer**: (a) **Hardness**: Metals are typically hard and strong, due to the strong metallic bonds holding the atoms together in a crystal lattice structure. However, their hardness can vary depending on the metal. For example, iron is strong and hard, while sodium and potassium are soft. * **Non-metals**: Non-metals can be hard or soft. For example, diamond, a form of carbon, is the hardest known natural substance. However, sulfur and phosphorus are soft, and iodine is a soft solid that can be easily crushed. (b) **Lustre**: Metals have a shiny, reflective surface, which makes them appear lustrous. This is due to the presence of delocalized electrons that can reflect light. * **Non-metals**: Non-metals can have various appearances, and don't share the same luster as metals. Some non-metals are dull and non-reflective, while others can be brightly coloured. For example, sulfur has a yellow appearance, while phosphorus is white. (c) **Tensile Strength**: Tensile strength refers to the resistance of a material to breaking under tension. Metals generally have high tensile strength, meaning they can withstand a significant amount of pulling stress without breaking. * **Non-metals:** Non-metals are generally not as strong as metals and often have low tensile strength. Their properties range from very weak to very strong but they tend to be brittle rather than strong under tension. 6. What do you understand by rusting of iron? Give any four preventive measures. **Answer**: Rusting of iron is the process called corrosion. It is the oxidation of iron to form iron oxide (Fe2O3). This process occurs when iron is exposed to air and moisture. The corrosion is a chemical reaction: $$ 4Fe(s) + 3 O_2(g) + 2H_2O(l) \longrightarrow 2 Fe_2O_3(s)+2H_2O(l) $$ Here are four preventive measures to minimize rusting: * **Painting:** Applying a coating of paint acts as a barrier that prevents the iron from coming into contact with air and moisture. * **Galvanization:** Coating the iron with a thin layer of zinc, which is more reactive than iron. The zinc will corrode first, protecting the iron. * **Oiling/Greasing:** Applying a thin coat of oil or grease forms a protective film that prevents contact with moisture and oxygen. * **Tin-plating:** Coating the iron with a thin layer of tin, which is less reactive than iron. Tin plating is commonly used for cans. 7. What is reactivity series of metals and how it helps in telling the reactivity of various metals with dil. HCI. **Answer**: The reactivity series of metals shows the order of reactivity of various metals, based on their tendency to lose electrons and form positively charged ions. The metals that are more reactive lose electrons more easily and readily react with acids, resulting in the release of hydrogen gas. * In the reactivity series, the metals at the top are the most reactive and the metals at the bottom are the least reactive. For example, Potassium (K) is the most reactive metal, while Gold (Au) is the least reactive. The reactivity series can be used to predict whether a given metal will react with dilute hydrochloric acid (HCl) or not. * Metals located above hydrogen in the reactivity series will react with dilute HCl, producing hydrogen gas. These metals are considered more reactive than hydrogen. * Metals located below hydrogen in the reactivity series will not react with dilute HCl. These metals are considered less reactive than hydrogen. ### Section D Puzzle: | | 1 | 2 | 3 | 4 | 5 | |---|---|---|---|---|---| | **Across** | | | | | | | 1 | D | |  | | | | 2 |  | **M**| | | | | 3 | U |  | **L**|  | | | 4 |  | |  | **O**| | | 5 | C | | |  |**S** | | 6 |T | |  | | | | 7 |I | |  | | | | 8 |L |  |  | | | | 9 | |  | |  |**T**| | 10 | Y | |  | | | | **Down** | 1 | 2 | 3 | 4 | 5 | | 1 |  | D |  | |  | 2 |  | U |  | | | | 3 |  | C |  | | | | 4 |  | T |  | | | | 5 |  |I |  | | | | 6 |  | L |  | | | | 7 |  | I |  | | | | 8 |  |T |  | | | | 9 |  | Y |  | | | | 10 |  |R |  | | | Across: 2. Elements which are hard solid, malleable and ductile: **Metals** 3. The property of a metal by virtue of which its surface has a shine: **Lustre** 4. Metal which is a main component of a stainless steel alloy: **Iron** Down: 1. The property by which metal can be drawn into wires: **Ductility** 5. The property of a metal which produces sound when struck with a hammer: **Sonorous** ## Objective ### Level - 1 Multiple Choice Questions (Single Option Correct) 1. Which metal will replace copper from CuSO4 solution? **Answer**: (D) All of them 2. Arrange the metals A, B and C in order of decreasing reactivity keeping in view the following reactions: A+BSO4→ASO4 +B B+2CNO3→B(NO3)2 + 2C A+C2O→AO+2C **Answer**: (D) A > B > C 3. Which one of the following is not a noble metal? **Answer**: (C) Iron 4. Which is not the characteristic property of gold? **Answer**: (B) Highly reactive 5. Which of the following is not used for making ornaments? **Answer**: (D) Zinc 6. Which is not the constituent of steel? **Answer**: (D) Zinc 7. Which is not the constituent of bronze? **Answer**: (D) None of these 8. Which is an alloy of aluminium? **Answer**: (C) Both (A) and (B) 9. Galvanised iron is protected from rust, because it has a coating of. **Answer**: (D) Zn 10. Which is/are the alloy of iron? **Answer**: (D) All of them 11. Which of the following is liquid metal? **Answer**: (B) Sodium ### Fill in the Blanks 16. The number of metals are much _______ than non-metals. **Answer**: more 17. Examples of non-metals are _______ and _______ . **Answer**: hydrogen & nitrogen 18. _______ metals exist in free state. **Answer**: Noble 19. _______ are harder than non-metals. **Answer**: Metals 20. _______ is an ore having two metals atoms. **Answer**: Copper pyrites ### True or False 21. Noble gases are found in free state. **Answer**: True 22. Non-metals are generally brittle. **Answer**: True 23. Iodine is lustrous and is a metal. **Answer**: True 24. All metals exist in solid form at room temperature. **Answer**: False 25. Gold is bad conductor of heat. **Answer**: False ### Match the Following 26. Match the Column - I with Column – II. Column – I Column – II (i) Na (a) Amphoteric oxide (ii) MgO (b) Weak base (iii) NH4OH (c) Basic oxide (iv) Al2O3 (d) Soft metal **Answer**: (i→ d), (ii → c), (iii → b), (iv→ a) 27. Match the Column – I with Column – II. Column – I Column – II (i) Marble (a) A poisonous gas (ii) Graphite (b) Fire extinguishers (iii) Carbon dioxide (c) Lead pencils (iv) Carbon monoxide (d) Lime stone **Answer**: (i→ d), (ii → c), (iii → b), (iv → a) ### Level - II Multiple Choice Questions (Single Option Correct) 1. Brass is an alloy of **Answer**: (A) Cu, Zn 2. Chemical composition of galena **Answer**: (C) PbS 3. Give the constituent of fluorspar **Answer**: (B) CaF2 4. Duralumin is made up of. **Answer**: (D) Al, Mg, Zn, Fe 5. Which of the following do not react readily with water? **Answer**: (D) Copper 6. The gas liberated when water reacts with metal **Answer**: (C) Hydrogen 7. Phosphorous is kept in water to protect it from **Answer**: (B) Oxygen 8. The main metal used in thermite welding is **Answer**: (A) Aluminium 9. Which of the following lie above hydrogen in the activity series? **Answer**: (A) Aluminium 10. Which one of the following metal is brittle at room temperature? **Answer**: (D) Tin 11. Copper on corrosion turns. **Answer**: (C) Green, CuCO3, Cu(OH)2 12. The correct order of metals in the reactivity series is. **Answer**: (B) Ca > Zn > Cu > Mg 13. Non-metals are generally **Answer**: (D) Brittle 14. Which of the following is not a property of mercury? **Answer**: (C) Ductility 15. Which of the following is the most abundant metal in the earth's crust? **Answer**: (C) Al ### Level - 3 Multiple Choice Questions (Single Option Correct) 1. The most abundant element in the earth's crust **Answer**: (A) Oxygen 2. A highly reactive element X is stored in kerosene oil. It reacts violently with air to give a compound Y which dissolves in water. He aqueous solution of Y changes red litmus blue. The element X is **Answer**: (A) Calcium 3. Aguaregia is mixture of **Answer**: (A) 1 volume of conc. HCI and 3 volumes of conc. HNO3 4. A mineral is called ore, if **Answer**: (B) A metal can be extracted from it 5. Non-metals are majority present as **Answer**: (D) Both (A) and (C) 6. Select the one that occurs in native form **Answer**: (D) Gold 7. Which of the following statements is true? **Answer**: (C) A mineral cannot be an ore 8. For vulcanization of rubber we use which one of the following non-metal? **Answer**: (B) Sulfur 9. The metal which melts at around room temperature is **Answer**: (B) Gallium 10. Choose the one among the following which does not exhibit lustre: **Answer**: (B) Iodine 11. Silicon is very well known for its **Answer**: (C) Semi conductivity 12. Bromine is **Answer**: (A) A liquid at room temperature