CBSE Class 10 Chemistry Metals And Non Metals Worksheet Set E

Multiple Choice Questions

Question. Which of the following property is generally not shown by metals ?
(a) Electrical conduction
(b) Sonorous in nature
(c) Dullness
(d) Ductility
Answer: (c)

Question. The ability of metals to be drawn into thin wire is known as :
(a) Ductility
(b) Malleability
(c) Sonorousity
(d) Conductivity
Answer: (a)

Question. Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same ?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)
Answer: (d)

Question. Which one of the following metals do not react with cold as well as hot water ?
(a) Na
(b) Ca
(c) Mg
(d) Fe
Answer: (d)

Question. Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam ?
(a) \( \text{FeO} \)
(b) \( \text{Fe}_2\text{O}_3 \)
(c) \( \text{Fe}_3\text{O}_4 \)
(d) \( \text{Fe}_2\text{O}_3 \) and \( \text{Fe}_3\text{O}_4 \)
Answer: (c)

Question. What happens when calcium is treated with water ?
(i) It does not react with water.
(ii) It reacts violently with water.
(iii) It reacts less violently with water.
(iv) Bubbles of hydrogen gas formed stick to the surface of calcium :
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (ii)
(d) (iii) and (iv)
Answer: (d)

Question. Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg) ?
(a) \( \text{H}_2\text{SO}_4 \)
(b) \( \text{HCl} \)
(c) \( \text{HNO}_3 \)
(d) All of these
Answer: (c)

Question. Silver articles become black on prolonged exposure to air. This is due to the formation of
(a) \( \text{Ag}_3\text{N} \)
(b) \( \text{Ag}_2\text{O} \)
(c) \( \text{Ag}_2\text{S} \)
(d) \( \text{Ag}_2\text{S} \) and \( \text{Ag}_3\text{N} \)
Answer: (c)

Question. Which of the following are not ionic compounds ?
(i) \( \text{KCl} \)
(ii) \( \text{HCl} \)
(iii) \( \text{CCl}_4 \)
(iv) \( \text{NaCl} \)
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iii)
Answer: (b)

Question. Which one of the following properties is not generally exhibited by ionic compounds ?
(a) Solubility in water.
(b) Electrical conductivity in solid state.
(c) High melting and boiling points.
(d) Electrical conductivity in molten state.
Answer: (b)

Question. Match the following
Column I Property of metal: (a) is a liquid at room temperature. (b) can be easily cut with a knife. (c) is the best conductor of heat. (d) is a poor conductor of heat.
Column II Metal: (i) Sodium (ii) Mercury and lead (iii) Mercury (iv) Silver
Answer: (a) (iii), (b) (i), (c) (iv), (d) (ii).

Question. Fill in the blanks
(a) The earthy impurities associated with mineral used in metallurgy are called ................. .
(b) An ................. is a homogeneous mixture of two or more metals, or a metal and a non-metal.
(c) Non-metals react with hydrogen to form ................. .
Answer: (a) Gangue, (b) alloy, (c) hydrides.

Very Short Answers Type Questions

Question. How are covalent bonds formed ?
Answer: Covalent bonds are formed by the sharing of electrons between atoms. By sharing their outermost valence electrons, atoms can fill up their outer electron shell and gain stability.

Question. Silver articles become black when kept in open for some time, whereas copper vessels lose their shiny brown surfaces and gain a green coat when kept in open. Name the substances present in air with which these metals react and write the name of the products formed.
Answer: Silver articles become black when kept in open for some time because silver reacts with sulphide compounds such as hydrogen sulphide present in the air to form silver sulphide (\( \text{Ag}_2\text{S} \)) whereas copper reacts slowly with \( \text{CO}_2 \) and water present in the air to form green coating of mixture of copper carbonate and copper hydroxide.

Question. A student added few pieces of aluminium metal to two test tubes A and B containing aqueous solution of iron sulphate and copper sulphate. In the second part of her experiment, she added iron metal to another test tube C and D containing aqueous solution of aluminium sulphate and copper sulphate. In which test tube or test tubes will she observe colour change ? On the basis of this experiment state which one is the most reactive metal and why ?
Answer: The student will observe colour changes in test tubes A, B, and D. In test tube A: \( \text{Al}(s) + \text{FeSO}_4(aq) \text{ (green sol}^n) \rightarrow \text{Al}_2(\text{SO}_4)_3(aq) + \text{Fe}(s) \text{ (colourless)} \). In test tube B: \( \text{Al}(s) + \text{CuSO}_4(aq) \text{ (blue sol}^n) \rightarrow \text{Al}_2(\text{SO}_4)_3(aq) + \text{Cu}(s) \text{ (colourless)} \). In test tube D: \( \text{Fe}(s) + \text{CuSO}_4(aq) \text{ (blue sol}^n) \rightarrow \text{FeSO}_4(aq) + \text{Cu}(s) \text{ (pale green sol}^n) \). On the basis of this experiment, Aluminium is the most reactive metal because it can displace both Iron and Copper from their respective salt solutions. The reactivity order is \( \text{Al} > \text{Fe} > \text{Cu} \).

Question. Name one metal which has a low melting point.
Answer: Cesium.

Question. What name is given to those metal oxides which show basic as well as acidic behaviour ?
Answer: Amphoteric oxides.

Question. Name two metals which form amphoteric oxides.
Answer: Aluminium and zinc.

Question. Give an example of a metal which :
(a) is a liquid at room temperature.
(b) can be easily cut with a knife.
(c) is the best conductor of heat.
(d) is a poor conductor of heat.
Answer: (a) Metal that exists in liquid state at room temperature → Mercury (b) Metal that can be easily cut with a knife → Sodium, Potassium (c) Metal that is the best conductor of heat → Silver, Gold (d) Metals that are poor conductors of heat → Mercury and lead

Question. Explain the meanings of malleable and ductile.
Answer: Malleable : Substances that can be converted into thin sheets by beating are called malleable. Most of the metals are malleable. Gold and silver are most malleable metals. Ductile : Substances that can be drawn into thin wires are called ductile. Most of the metals are ductile. Gold is the most ductile metal.

Question. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
Answer: Copper does not react with cold water, hot water, or steam. However, iron reacts with steam. If the hot water tanks are made of steel (an alloy of iron), then iron would react vigorously with the steam formed from hot water.
\( 3\text{Fe} + 4\text{H}_2\text{O} \rightarrow \text{Fe}_3\text{O}_4 + 4\text{H}_2 \)
That is why copper is used to make hot water tanks and not steel.

Question. In the formation of a compound \( \text{XY}_2 \) atom X gives one electron to each Y atom. What is the nature of bond in \( \text{XY}_2 \) ? Give two properties of \( \text{XY}_2 \).
Answer: \( \text{XY}_2 \) has ionic bonds. \( \text{XY}_2 \) would conduct electricity when dissolved in water and \( \text{XY}_2 \) would have high melting and boiling point.

Question. An element ‘A’ has two electrons in the outermost shell of its atom and combines with an element ‘B’ having seven electrons in the outermost shell, forming the compound \( \text{AB}_2 \). The compound when dissolved in water conducts electric current. Giving reasons, state the nature of chemical bond in the compound.
Answer: \( \text{AB}_2 \) forms ionic bonds because an aqueous solution of an ionic compound conducts electricity because there are plenty of free ions in the solution which are able to conduct electric current.

Question. What happens when a copper rod is placed in silver nitrate solution ?
Answer: Copper displaces silver as it is more reactive. A blue coloured solution will be formed and grey coloured solution will be deposited at the bottom of container.

Question. Aluminium strips were placed in a solution of copper sulphate. After one hour, it was observed that the colour of solution changes. What will be the colour of the solution ? Give reasons.
Answer: Aluminium will displace \( \text{Cu} \) from copper sulphate solution. As a result, the solution will be colourless.

Question. A piece of granulated \( \text{Zn} \) was dropped into copper sulphate solution. Write down the colour change that you will observe.
Answer: When a piece of granulated \( \text{Zn} \) was dropped into copper sulphate solution, blue colour solution become colourless, reddish brown \( \text{Cu} \) gets deposited.

Short Answers Type Questions

Question. What are amphoteric oxides ? Give an example. Write balanced chemical equations to justify your answer.
Answer: Those oxides which behave as both acidic and basic oxides are called amphoteric oxides.
Example : \( \text{Al}_2\text{O}_3 \) (Alumina)
(a) \( \text{Al}_2\text{O}_3 + 6\text{HCl} \rightarrow 2\text{AlCl}_3 + 3\text{H}_2\text{O} \)
(b) \( \text{Al}_2\text{O}_3 + 2\text{NaOH} \rightarrow 2\text{NaAlO}_2 + \text{H}_2\text{O} \)

Question. Give reason :
(a) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
(b) Aluminium is a highly reactive metal; still it is widely used in making cooking utensils.
Answer: (a) Carbonate and sulphide ores are usually converted into oxides during the process of extraction because obtaining a metal from its metal oxide is much easier than from metal carbonates and sulphides. (b) Aluminium is highly reactive metal still it is widely used in making cooking utensils because it reacts with \( \text{O}_2 \) present in air to form aluminium oxide that forms a protective layer and protects the metal from corrosion.

Question. Name a metal of medium reactivity and write three main steps in the extraction of this metal from its sulphide ore.
Answer: Zinc. The steps inolved in extraction of zinc from zinc sulphide are :
(a) Roasting of sulphide ore in the presence of air to convert it into metal oxide.
\( 2\text{ZnS}(s) + 3\text{O}_2(g) \xrightarrow{\text{Roasting}} 2\text{ZnO}(s) + 2\text{SO}_2(g) \)
(b) Reduction of metal oxide with carbon to get the free metal.
\( \text{ZnO}(s) + \text{C}(s) \rightarrow \text{Zn}(s) + \text{CO}(g) \)
(c) Refining of impure metal to get pure metal.

Question. Given below are the steps for the extraction of copper from its ore. Write the chemical equation of the reactions involved in each case.
(a) Roasting of copper(I) sulphide.
(b) Reduction of copper(I) oxide from copper(I) sulphide
(c) Electrolytic refining.
Answer: (a) \( 2\text{Cu}_2\text{S}(s) + 3\text{O}_2(g) \xrightarrow{\text{Roasting}} 2\text{Cu}_2\text{O}(s) + 2\text{SO}_2(g) \)
(b) \( 2\text{Cu}_2\text{O}(s) + \text{Cu}_2\text{S}(s) \xrightarrow{\text{Heat}} 6\text{Cu}(s) + \text{SO}_2(g) \)
(c) At cathode : \( \text{Cu}^{2+} + 2\text{e}^- \rightarrow \text{Cu} \) (Copper deposits). At anode : \( \text{Cu} - 2\text{e}^- \rightarrow \text{Cu}^{2+} \) (Copper ion goes into electrolyte).

Question. Explain the following :
(a) Sodium chloride is an ionic compound which does not conduct electricity in solid state where as it does conduct electricity in molten state as well as in aqueous solution.
(b) Reactivity of aluminium decrease if it is dipped in nitric acid.
(c) Metals like calcium and magnesium are never found in their free state in nature.
Answer: (a) Sodium chloride is an ionic compound but it conducts electricity only in molten and aqueous state because in molten and aqueous form the compound liberate to give ions. These ions move freely and hence conduct electricity. (b) Reactivity of aluminium decreases if it is dipped in nitric acid because it is a strong oxidising reagent. The layer of aluminium oxide (\( \text{Al}_2\text{O}_3 \)) prevents further reaction of aluminium due to which its reactivity decreases. (c) Metals like calcium and magnesium are never found in their free states in nature they occur in the form of ores because these metals are present on the top of the reactivity series. They are highly reactive that they react with gases and surrounding elements, form compounds and thus are not found in free state.

Question. Write the electronic configuration of two elements X and Y whose atomic numbers are 20 and 17 respectively. Write the molecular formula of the compound formed when element X reacts with element Y. Draw electron dot structure of the product and also state the nature of the bond formed between both the elements.
Answer: \( \text{X} = 20 : 2, 8, 8, 2 \); \( \text{Y} = 17 : 2, 8, 7 \). The molecular formula is \( \text{XY}_2 \). Electron-dot structure shows X losing 2 electrons to form \( \text{X}^{2+} \) and two Y atoms each gaining one electron to form \( \text{Y}^- \). The nature of bond will be ionic.

Question. From amongst the metals sodium, calcium, aluminium, copper and magnesium, name the metal :
(a) Which reacts with water only on boiling,
(b) Another which does not react even with steam.
Answer: (a) Aluminium (b) Copper.

Question. What is a covalent bond ? What type of bond exists in (a) \( \text{CCl}_4 \), (b) \( \text{CaCl}_2 \) ?
Answer: The chemical bond formed by the sharing of electrons between two atoms is known as a covalent bond. (a) Covalent bonds in \( \text{CCl}_4 \), (b) Ionic bonds in \( \text{CaCl}_2 \).

Question. What is an ionic bond ? What type of bond is present in oxygen molecule ?
Answer: The chemical bond formed by the transfer of electrons from one atom to another is known as an ionic bond. Covalent bond is present in an oxygen molecule.

Question. (a) Draw the electron-dot structure of a hydrogen chloride molecule.
(b) (i) Which inert gas does the H atom in HCl resemble in electron arrangement ? (ii) Which inert gas does the Cl atom in HCl resemble in electron arrangement ?
Answer: (a) Electron-dot structure of \( \text{HCl} \) shows a shared pair of electrons between \( \text{H} \) and \( \text{Cl} \). (b) (i) Helium, (ii) Argon.

Question. Why is sodium chloride soluble in water but not in kerosene and petrol ?
Answer: Water is a polar solvent and sodium chloride is an ionic compound. When sodium chloride is dissolved in water, it dissociates into ions. Therefore, it dissolves in it. On the other hand, kerosene and petrol are non-polar solvents. These cannot overcome the strong electrostatic force of attraction between the ions. And hence, \( \text{NaCl} \) does not dissolve into it.

Question. State reasons for the following observations :
(a) The shining surface of some metals becomes dull when exposed to air for a long time.
(b) Zinc fails to evolve hydrogen gas on reacting with dilute nitric acid.
(c) Metal sulphides occur mainly in rocks but metal halides occur mostly in sea and lake waters.
Answer: (a) It is because metal reacts with substances present in atmosphere to form surface compounds which make it dull. (b) It is because dil. \( \text{HNO}_3 \) is an oxidising agent therefore zinc gives \( \text{NO} \) and not \( \text{H}_2 \) with dil. \( \text{HNO}_3 \). (c) It is because sea water contains sodium chloride due to which metal halides are formed, whereas sulphur is found below rocks. Therefore, metal – sulphides are formed in rocks.

Long Answers Type Questions

Question. (a) By the transfer of electrons, illustrate the formation of bond in magnesium chloride and identify the ions present in this compound.
(b) Ionic compounds are solids. Give reasons.
(c) With the help of a labelled diagram show the experimental set up of action of steam on a metal.
Answer: (a) \( \text{Mg} \rightarrow \text{Mg}^{2+} + 2\text{e}^- \); \( \text{Cl} + \text{e}^- \rightarrow \text{Cl}^- \). Ions present are \( \text{Mg}^{2+} \) and \( \text{Cl}^- \). (b) Ionic compounds are solids and are somewhat hard because of the strong force of attraction between the positive and negative ions. These compounds are generally brittle and break into pieces when pressure is applied. (c) The diagram shows the action of steam on a metal where glass-wool soaked in water is heated to produce steam, which reacts with metal samples in a delivery tube to produce hydrogen gas collected over water.

Question. (a) List in tabular form three chemical properties on the basis of which we can differentiate between a metal and a non-metal.
(b) Give reasons for the following:
(i) Most metals conduct electricity well.
(ii) The reaction of iron (III) oxide [\( \text{Fe}_2\text{O}_3 \)] with heated aluminimum is used to join cracked machine parts.
Answer: (a) Metals react with oxygen to form basic oxides, while non-metals form acidic or neutral oxides. Metals react with water to produce metal hydroxide and hydrogen gas, while non-metals do not react with water. Metals form ionic hydrides with hydrogen, while non-metals form covalent hydrides. (b) (i) Metals have free electrons which move through the metal and conduct electric current. (ii) \( \text{Fe}_2\text{O}_3(s) + 2\text{Al}(s) \rightarrow \text{Al}_2\text{O}_3(s) + 2\text{Fe}(l) + \text{Heat} \). This is thermite reaction. Iron is produced in molten form and used to join the tracks.

Question. (a) Write the steps involved in the extraction of pure metals in middle of the activity series from carbonate ores.
(b) How is copper extracted from its sulphide ore ? Explain the various steps supported by chemical equations. Draw labelled diagram for electrolytic refining of copper.
Answer: (a) Extraction of pure metals from carbonate ores involves: (i) Concentration of ore. (ii) Calcination: Carbonate ores are heated strongly in the absence of air. Ex: \( \text{ZnCO}_3(s) \xrightarrow{\text{Heat}} \text{ZnO}(s) + \text{CO}_2(g) \). (iii) Reduction: Metal oxide is reduced using carbon or a more reactive metal. Ex: \( \text{ZnO} + \text{C} \rightarrow \text{Zn} + \text{CO} \). (iv) Refining: Finally, the metal is refined. (b) Copper is extracted from copper glance (\( \text{Cu}_2\text{S} \)) by first roasting it and then reducing. Equations: \( 2\text{Cu}_2\text{S} + 3\text{O}_2 \rightarrow 2\text{Cu}_2\text{O} + 2\text{SO}_2 \) and \( 2\text{Cu}_2\text{O} + \text{Cu}_2\text{S} \rightarrow 6\text{Cu} + \text{SO}_2 \). Electrolytic refining uses impure copper as anode and pure copper as cathode in acidified \( \text{CuSO}_4 \) solution.

Question. (a) What are metals ? Name five metals.
(b) Name a metal which is so soft that it can be cut with a knife.
(c) Name the metal which is the best conductor of heat and electricity.
(d) What happens when a metal reacts with dilute hydrochloric acid ? Explain with the help of an example.
Answer: (a) Metals are elements that conduct heat and electricity, and are malleable and ductile. Example: Iron, aluminium, copper, gold and silver. (b) Sodium. (c) Silver. (d) When a metal reacts with dilute hydrochloric acid, it forms metal chloride and hydrogen gas. Example: Magnesium reacts rapidly with dilute hydrochloric acid to form magnesium chloride and hydrogen: \( \text{Mg}(s) + 2\text{HCl}(aq) \rightarrow \text{MgCl}_2(aq) + \text{H}_2(g) \).

Question. Describe two methods for the concentration of ores.
Answer: (a) Froth Floatation method : Used to remove gangue from sulphide ores. Powdered ore suspension is mixed with pine oil. Metal part forms froth which is skimmed off. (b) Magnetic separation method: Used when either ore or impurities are magnetic. Powdered ore falls on a moving belt over an electromagnetic roller. Magnetic particles form a separate heap.

Question. Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.
Answer: For low reactivity metals (e.g., Mercury): Sulphide ore is roasted to form oxide, then the oxide is further heated for reduction to metal. Equation: \( 2\text{HgS} + 3\text{O}_2 \rightarrow 2\text{HgO} + 2\text{SO}_2 \). For medium reactivity metals (e.g., Zinc): Sulphide ore is roasted to obtain oxide, then the oxide is reduced using carbon. Equations: \( 2\text{ZnS} + 3\text{O}_2 \rightarrow 2\text{ZnO} + 2\text{SO}_2 \) and \( \text{ZnO} + \text{C} \rightarrow \text{Zn} + \text{CO} \).

Question. State five uses of metals and non-metals.
Answer: Uses of metals: (a) Copper/Aluminium for electrical wires. (b) Zinc for galvanizing. (c) Iron/Copper/Aluminium for utensils. (d) Lead for car batteries. (e) Aluminium foil for packaging. Uses of non-metals: (a) Hydrogen for hydrogenation. (b) Carbon for electrodes. (c) Nitrogen for fertilizers. (d) Sulphur for sulphuric acid. (e) Liquid hydrogen as rocket fuel.

Question. (a) List in tabular form any three chemical properties on the basis of which metals and non-metals are differentiated.
(b) State two ways to prevent the rusting of iron.
Answer: (a) Metals lose electrons to form positive ions (electro-positive), whereas non-metals gain electrons to form negative ions (electro-negative). Metals react with dilute acids to liberate hydrogen gas, while non-metals do not. Metal oxides are basic, while non-metal oxides are acidic. (b) Painting and galvanization.

Assertion and Reasoning Based Questions

Question. Assertion (A) : Alloys are commonly used in electrical heating devices like electric iron and heater.
Reason (R) : Resistivity of an alloy is generallly higher than that of its constituent metals but the alloys have low melting points than their constituent metals.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (b)

Question. Assertion : Sodium is kept immersed in kerosene oil.
Reason : Sodium is very reactive metal.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (a)

Question. Assertion : Platinum, gold and silver are used to make jewellery.
Reason : It is because they are very lustrous.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (a)

Question. Assertion : Copper is used to make hot water tanks and not steel (an alloy of iron).
Reason : Copper does not react with hot water.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (c)

Question. Assertion : The metal sulphides and carbonates are converted to metal oxides in the process of extraction of metal from them.
Reason : It is because it is easier to obtain metal from its oxide.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.
Answer: (c)

Creating Based Questions

Question. Write any four properties shown by the metal gold, which allowed our ancestors to choose it for preparation of ornaments.
Answer: (a) Gold is lustrous in nature. (b) Gold is malleable which allows it to be converted into different shapes and designs. (c) Gold is ductile, due to which it can be drawn into wires. (d) Gold is not reactive metal, hence can be used as ornaments for daily wearing purposes.

Question. (a) Which types of metals can be obtained in their pure form by just heating their oxides in air ? Give one example.
(b) Consider the reaction given below used to obtain Manganese metal in pure form :
\( 3\text{MnO}_2(s) + 4\text{Al}(s) \rightarrow 3\text{Mn}(l) + 2\text{Al}_2\text{O}_3(s) + \text{Heat} \)
(i) What type of reaction is it ?
(ii) What is the role of aluminium in this reaction ?
Answer: (a) Metals low in activity series can be reduced by just heating their oxides. Example: mercury. \( 2\text{HgO}(s) \xrightarrow{\text{Heat}} 2\text{Hg}(l) + \text{O}_2(g) \). (b) (i) The given reaction is a displacement reaction. (ii) Aluminium is used as a reducing agent.

Question. Give reasons for following :
(a) Copper is used for making electrical circuits but brass is not.
(b) Steel is used for making utensil but pure iron is not.
Answer: (a) Copper is pure metal and its electrical conductivity is high, whereas brass is an alloy and its conductivity is lower. (b) Pure iron is soft and changes shape on heating, while steel is an alloy that is hard and retains its shape.

Question. Recently galvanization industry has bloomed due to extensive use of galvanization process.
(a) What is ‘galvanization’ ?
(b) Mention two areas where it is found in use.
(c) Sometimes zinc coating is broken, still the object remains protected, give reasons.
Answer: (a) Galvanization is a method of protecting steel and iron from rusting by coating with a thin layer of zinc. (b) Cooking utensils and industrial equipments. (c) Zinc is more reactive than iron and hence can be easily oxidised. Thus, when zinc layer breaks down, the zinc continues to react and get oxidised. Hence, iron object remains protected.

Question. A farmer was working with an agricultural machine when he observed a crack. He realised that if the crack is not mended it will lead to further damage of the machine. He reached out to the local mechanic who repaired the crack with some iron compound and aluminium. What is the technique used by the local mechanic ? Write relevant chemical reaction equation for the same.
Answer: The mechanic used the thermite reaction. Iron(III) oxide is reacted with aluminium. The reaction is accompanied by evolution of large amount of heat, which melts the metal to fill the crack.
\( \text{Fe}_2\text{O}_3(s) + 2\text{Al}(s) \rightarrow 2\text{Fe}(l) + \text{Al}_2\text{O}_3(s) + \text{Heat} \)

Paragraph/Table and Case Study Based Questions

The reactivity series of metals, also known as the activity series, refers to the arrangement of metals in the descending order of their reactivities. Metals tend to readily lose electrons and form cations. Most of them react with atmospheric oxygen to form metal oxides. The following graph shows the activity series of metals plotted against electronegativity and E°, volts.

Question. Which of the following is the correct arrangement of the given metals in ascending order of their reactivity?
Zinc, mercury, aluminium, Sodium
(a) Zinc > mercury > aluminium > Sodium
(b) Sodium > aluminium > mercury > Zinc
(c) Sodium > Zinc > aluminium > mercury
(d) Sodium > aluminium > Zinc > mercury
Answer: (d)

Question. Oxides of moderately reactive metals like Zinc, Iron, Nickel, Tin, Copper etc. are reduced by using:
(a) hydrogen as reducing agent
(b) Carbon as reducing agent
(c) Sodium as reducing agent
(d) magnesium as reducing agent
Answer: (c)

Question. In the given reaction, \( \text{Al}_2\text{O}_3 + \text{NaOH} \rightarrow \text{X} + \text{H}_2\text{O} \)
(a) \( \text{NaAlO}_2 \)
(b) \( \text{Na}_3\text{Al} \)
(c) \( \text{Na}_2\text{O}_3 \)
(d) \( \text{NaAl}_2\text{O}_3 \)
Answer: (a)

Question. Generally, metals react with acids to give salt and hydrogen gas. Which of the following acids do not give hydrogen gas on reacting with metals (except Mn and Mg)?
(a) \( \text{H}_2\text{SO}_4 \)
(b) \( \text{HCl} \)
(c) \( \text{HNO}_3 \)
(d) All of these
Answer: (c)

Question. An aluminium strip is kept immersed in freshly prepared ferrous sulphate solution taken in a test tube, the change observed is that
(a) Green solution slowly turns brown
(b) Lower end of test tube become slightly warm
(c) A colourless gas with the smell of burning sulphur is observed
(d) Light green solution changes to blue.
Answer: (a)

Reactive metals can displace less reactive metals from their compounds in solution or molten form. All metals are not equally reactive. Displacement reactions give better evidence about the reactivity of metals. If metal A displaces metal B from its solution, it is more reactive than B. The reactivity series is a list of metals arranged in the order of their decreasing activities.

Question. What is the basis of formation of reactivity series?
Answer: Displacement reactions of metals form the basis of reactivity series.

Question. If metal A displaces metal B from its solution. What type of reaction is it?
Answer: Displacement of one metal by other is a type of displacement reaction.

Question. Give one example of displacement reaction.
Answer: Reaction of iron nails with copper sulfate solution is an example of displacement reaction.

Question. State whether the statement is true or false. The reactivity series is a list of metals arranged in the order of their size.
Answer: Reactivity series is a series that gives information about the reactivity of metals. Therefore, the given statement is false.

Metals are lustrous, malleable, ductile and are good conductors of heat and electricity. They can form positive ions by losing electrons to non-metals. Metals combine with oxygen to form basic oxides. Metals above hydrogen in the Activity series can displace hydrogen from dilute acids. The extraction of metals from their ores and then refining them for use is known as metallurgy.

Question. Which of the following pairs will give displacement reactions?
(a) \( \text{MgCl}_2 \) solution and aluminium metal.
(b) \( \text{NaCl} \) solution and copper metal.
(c) \( \text{FeSO}_4 \) solution and silver metal.
(d) \( \text{AgNO}_3 \) solution and copper metal.
Answer: (d)

Question. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be:
(a) Calcium
(b) Silicon
(c) Iron
(d) Carbon
Answer: (a)

Question. Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying paint
(b) Applying a coating of zinc
(c) Applying grease
(d) All of these
Answer: (b)

Question. Write the name of the compound, when iron is corroded?
(a) Rust: hydrated iron (III) oxide (\( \text{Fe}_2\text{O}_3\cdot\text{xH}_2\text{O} \))
(b) Rust: (\( \text{Fe}_2\text{O}_3 \))
(c) \( \text{Al}_2\text{O}_3\cdot2\text{H}_2\text{O} \)
(d) None of these
Answer: (a)

Question. Why copper is used to make hot water tanks and not steel (an alloy of iron)?
(a) Because copper reacts with hot water.
(b) Because copper does not reacts with cold, hot water or steam while iron reacts vigorously with hot steam and makes iron oxide.
(c) Because copper is a good conductor of heat and electricity.
(d) All of these
Answer: (b)

Question. S. No. Metals Non-metals
1. Lustrous Non-lustrous
2. Hard Soft
3. Ductile Non-ductile
4. Malleable Non-malleable
5. Good conductors Poor conductors
(a) Give one example each of metals and non-metals.
(b) Explain ductility.
(c) Explain malleability.
(d) What is meant by luster ?
Answer: (a) Sodium is metal and chlorine is a non-metal. (b) Ductility is the property of metals in which they are converted into wires. (c) Malleability is the property of metals in which they are converted into thin sheets. (d) The shiny appearance of metal is known as luster.

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Question. (a) Name any one metal each which can be extracted by :
(i) reduction with carbon
(ii) electrolytic reduction
(iii) reduction with aluminium
(iv) reduction with heat alone
(b) Write a chemical equation for any of the above four parts.
Answer: (a) (i) Iron, (ii) Sodium, (iii) Manganese, (iv) Mercury. (b) \( 2\text{HgO}(s) \xrightarrow{\text{Heat}} 2\text{Hg}(l) + \text{O}_2(g) \).

Question. Give reason for the following :
(a) Why are copper and aluminium wires used as connecting wires ?
(b) Why is tungsten used for filaments of electric lamps ?
(c) Why is lead-tin alloy used for fuse wires ?
Answer: (a) They are good conductors of electricity. (b) It has a very high melting point. (c) It has a low melting point.

Question. Four metal rods labelled as P, Q, R and S along with their corresponding colours are shown below. Which of these rods could be made up of aluminium ?
Reddish brown (P); Blackish grey (Q); Dark grey (R); Silvery white (S)
(a) P (b) Q
(c) R (d) S
Answer: (d)

Question. List four important properties of aluminium which are responsible for its great demand in industry.
Answer: (1) Light weight, (2) Good conductor of heat and electricity, (3) Malleable, (4) Corrosion resistant.

Question. Which three chemical substances are obtained when electricity is passed through an aqueous solution of brine ? Write one industrial use of each.
Answer: (1) \( \text{NaOH} \): soap making, (2) \( \text{Cl}_2 \): water treatment, (3) \( \text{H}_2 \): making margarine.

Question. Differentiate between the following with suitable examples :
(a) Mineral and ore
(b) Corrosion and rancidity
(c) Malleability and ductility
Answer: (a) Mineral is a natural compound, Ore is a mineral from which metal is extracted profitably. (b) Corrosion is oxidation of metals, rancidity is oxidation of fats. (c) Malleability is into sheets, ductility is into wires.

Question. In column I different methods of extraction are given. Name the methods used for the extraction of metals given in Column II :
Column-I: (i) Reduction with carbon, (ii) Electrolytic reduction, (iii) Reduction with aluminium
Column-II: Al, Zn, Na, Fe, Mn, Pb
Answer: (i) Zn, Fe, Pb; (ii) Al, Na; (iii) Mn.

Question. In which form zinc metal is used from laboratory to prepare hydrogen ?
(a) Rod (b) Powder
(c) Filing (d) Granules
Answer: (d)

Question. Name the gas which is usually produced when dil. sulphuric acid reacts with a metal. Illustrate it with an example. How will you test the evolution of this gas ?
Answer: Hydrogen gas. Ex: \( \text{Zn} + \text{H}_2\text{SO}_4 \rightarrow \text{ZnSO}_4 + \text{H}_2 \). Test: Pop sound with burning matchstick.

Question. A metal ‘M’ is found in nature as its carbonate. It is used in the galvanization of iron. Identify ‘M’ and name its ore. How will you convert this ore into free metal ?
Answer: M is Zinc. Ore is Calamine (\( \text{ZnCO}_3 \)). Convert by calcination followed by reduction with carbon.

Question. (a) In electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode ?
(b) (i) What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube ? (ii) What type of reaction is this ? (iii) Write a balanced chemical equation to represent the above reaction.
Answer: (a) Water contains two parts of hydrogen and one part of oxygen. (b) (i) Yellow precipitate is formed. (ii) Double displacement. (iii) \( \text{Pb(NO}_3)_2 + 2\text{KI} \rightarrow \text{PbI}_2 + 2\text{KNO}_3 \).

Question. You are given samples of three metals—sodium, magnesium and copper. Suggest any two activities to arrange them in order of their decreasing reactivity.
Answer: (1) Reaction with water, (2) Displacement reactions.

Question. (a) What happens when an aqueous solution of sodium sulphate reacts with an aqueous solution of barium chloride ? State the physical conditions of reactants in which reaction between them will not take place. Write the balanced chemical equation for the reaction and also mention the type of reaction.
(b) What changes in the colour of iron nails and copper sulphate solution do you observe after keeping the iron nails in copper sulphate solution for about half an hour ?
Answer: (a) White precipitate of \( \text{BaSO}_4 \) is formed. Reaction won't happen in solid state. \( \text{Na}_2\text{SO}_4 + \text{BaCl}_2 \rightarrow \text{BaSO}_4 + 2\text{NaCl} \). Double displacement. (b) Blue solution turns green, nails become brownish.

Question. (a) Explain any two physical properties of ionic compounds giving reason.
(b) List any two metals found in free state in earth’s crust. Where are they located in activity series ?
(c) Metals towards the top of the activity series can not be obtained from their compounds by reducing with carbon. Why ?
Answer: (a) High melting point due to strong electrostatic forces; conduct electricity in molten state due to free ions. (b) Gold, Silver; located at the bottom. (c) They have more affinity for oxygen than carbon.

Question. A student placed Zn rod in \( \text{FeSO}_4 \) solution. After 10 hours when rod was taken out and it was observed that :
(a) Zn rod became thinner.
(b) Zn rod became thicker due to Iron deposition.
(c) Zn rod remains as it was.
(d) Zn rod has holes.
Answer: (b)

Question. Four test tubes marked I, II, III and IV were taken. 20 ml of \( \text{Al}_2(\text{SO}_4)_3 \) solution in water was poured in each of the test tubes. A piece of zinc metal was placed in test tube I, an iron nail was put in test tube II, copper turnings were put in test tube III and a clean aluminium strip was placed in test tube IV. No change was observed in any of the test tubes. The correct inference drawn is :
(a) Copper is more reactive than Aluminium.
(b) Zinc is more reactive than Aluminium.
(c) Zinc is more reactive than Copper.
(d) Zinc, Iron and Copper are less reactive than Aluminium.
Answer: (d)

Question. State reason for the following :
(a) Lemon is used for restoring the shine of tarnished copper vessels.
(b) A metal sulphide is converted into its oxide to extract the metal from the sulphide ore.
(c) Copper wires are used in electrical connections.
Answer: (a) Citric acid removes basic copper carbonate. (b) Reduction of oxides is easier. (c) It is a good conductor.

Question. Shashank was asked to carry out a displacement reaction which would show the following :
(i) Formation of colourless solution
(ii) Black deposits
The reactants he should use are :
(a) Fe(s) and \( \text{Al}_2(\text{SO}_4)_3 \)(aq)
(b) Al(s) and \( \text{FeSO}_4 \)(aq)
(c) Zn(s) and \( \text{CuSO}_4 \)(aq)
(d) Fe(s) and \( \text{ZnSO}_4 \)(aq)
Answer: (c)