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question_answer1) What is the colour of aqueous solution of and as observed in the laboratory?
question_answer2) A student took four test tubes I, II, III and IV containing aluminium sulphate, copper sulphate, ferrous sulphate and zinc sulphate solutions respectively. He placed an iron strip in each of them. In which test tube he found a brown deposite.
question_answer3) Aluminium sulphate and copper sulphate solutions were taken in two test tubes I and II, respectively. A few pieces of iron filings were then added to both the solutions. The four students A, B, C and D recorded their observations in the form of a table as given below. StudentSolution (I) Solution (II) A Colourless solution Light green Blue colour is retained B Colourless solution No change Blue colour solution Green C Colourless solution Light blue Blue colour solution Green D No change in colour Blue colour of solution fades Which student has recorded the correct observation?
question_answer4) What is the composition of aqua regia?
question_answer5) Aqueous solutions of zinc sulphate and iron sulphate were taken in test tubes I and II by four students A, B, C and D. Metal pieces of iron and zinc were dropped in the two solutions and observations made after several hours were recorded in the form of table as given below. Student Metal Solution Colour change of solution Deposit/coating obtained A Fe Turned green Silvery grey deposit Zn No change No change B Fe No change Black deposit Zn Colour faded Grey coating C Fe No change No change Zn Turned colourless Black deposit D Fe No change Grey deposit Zn No change Black deposit Which student has given the correct report?
question_answer6) When an aluminium strip is kept immersed in freshly prepared ferrous sulphate solution taken in a test tube. What change is observed in the test tube?
question_answer7) A student took Cu, Al, Fe and Zn strips separately in four test tubes labelled I, II, III and IV. He added 10 mL of freshly prepared ferrous sulphate solution to each test tube as shown below. In which test tubes black residue would be obtained?
question_answer8) An aqueous solution of zinc sulphate was taken in four test tubes. Zinc, iron, copper and aluminium pieces were dropped into separate test tubes. In which test tube reaction will be observed?
question_answer9) A cleaned aluminium foil was placed in an aqueous solution of zinc sulphate. When the aluminium foil was taken out of the zinc sulphate solution after 15 minutes, its surface was found to be coated with a silvery grey deposit. From the given observation, what can be concluded?
question_answer10) 10 mL of freshly prepared iron sulphate was taken in each of four test tubes. Strips of copper, iron, zinc and aluminium was introduced, each metal in a different test tube. A residue was obtained in two of them. The right pair of metals forming the precipitates is
question_answer11) A piece of granulated zinc was dropped into copper sulphate solution. After sometime, the colour of the solution changed from blue to colourless. Why?
question_answer12) Make a distinction between metals and non-metals with respect to the nature of their oxides.
question_answer13) How do we find whether a given element is a non-metal, if we know its electronic configuration?
question_answer14) Name a solvent in which electrovalent compounds are soluble and a solvent in which they are insoluble.
question_answer15) How do metals and non-metals combine?
question_answer16) Name three common types of metal ores that exist in nature.
question_answer17) What is anode mud?
question_answer18) Name the metals which are usually alloyed with gold to make it harder.
question_answer19) What is meant by 22 carat gold?
question_answer20) Name any two alloys whose electrical conductivity is less than that of pure metals.
question_answer21) Can rusting of iron nail occur in distilled water?
question_answer22) Name a metal which is non-lustrous and a non-metal which is lustrous.
question_answer23)
question_answer24) What is the valency of silicon with atomic number 14?.
question_answer25) Which of the following metals will melt at body temperature (37°C)? Gallium, magnesium, caesium, aluminium
question_answer26) Why does calcium float in water?
question_answer27) A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, where as Z is a good conductor of electricity. Identify X, Y and Z.
question_answer28) Name two metals which react with very dilute to evolve hydrogen gas.
question_answer29) Arrange the following metals in the decreasing order of reactivity. Na, K, Cu, Ag.
question_answer30) Show the electron transfer in the formation of from its elements.
question_answer31) Amongst the metals-sodium, calcium, aluminium, copper and magnesium, name the metal (a) which reacts with water only on boiling? (b) which does not react even with steam.
question_answer32) Is an alloy homogeneous or heterogeneous?
question_answer33) Name an alloy that contains a non-metal as one of its constituents
question_answer34) Name an alloy which has mercury as one of its constituents.
question_answer35) Although metals form basic oxides, name one metal which forms an amphoteric oxide?
question_answer36) Electrical wires have a coating of an insulating material. Name one such insulating material.
question_answer37) Name a non-metal, that is liquid at room temperature.
question_answer38) Name one property which is not shown by ionic compounds.
question_answer39) Name two metals that are obtained by electrolysis of their chlorides in molten State.
question_answer40) Which one of the following metals does not react with oxygen even at high temperatures? (a) Calcium (b) Gold (c) Sodium
question_answer41) Name one metal which reacts neither with cold water, nor with hot water, but reacts with heated steam to produce hydrogen gas.
question_answer42) Write the chemical equation for the reaction of hot aluminium with steam.
question_answer43) Why is tungsten metal selected for making filaments of incandescent lamp bulbs?
question_answer44) Write the chemical equation to represent the reaction taking place between sodium metal and cold water.
question_answer45) A green layer is gradually formed on a copper plate left exposed to air for a week in a bathroom. What could this green substance be?
question_answer46) What are amphoteric oxides? Give two examples.
question_answer47) reaction Out of two elements, X and Y which is more C reactive and why?
question_answer48) Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas? Write the chemical equations for both the reactions.
question_answer49) During extraction of metals, electrolytic refining is used to obtain pure metals. (a) Which material will be used as anode and cathode for refining of silver metal by this process? (b) Suggest a suitable electrolyte also. (c) In this electrolytic cell, where do we get pure silver after passing electric current?
question_answer50) Choose the metal (from the list given below) which can displace zinc from zinc sulphate solution. Lead, copper, magnesium, silver. Write the equation of the chemical reaction involved.
question_answer51) What happens when (a) is heated in the absence of oxygen? (b) a mixture of and is heated?
question_answer52) What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?
question_answer53) Give the formula of the stable binary compounds that would be formed by the combination of following pairs of elements (a) Mg and (b) U and (c) Al and (d) K and
question_answer54) A metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved.
question_answer55) Compound X and aluminium are used to join railway tracks. (a) Identify the compound X. (b) Name the reaction. (c) Write the equation for it.
question_answer56) A lady bought a new iron container and kept blue vitriol solution into it. On the next day, she found that the container becomes porous and the blue colour of the solution fades. She go to the shopkeeper and complained. But the shopkeeper argued that the container is of good quality and he is not giving her money back. An aware person Mohan came there and asked the matter and told that the container is of good quality and you have kept the wrong substance in it, so fault is all yours. On the basis of above passage answer the following questions (a) Why the container becomes porous when blue vitriol solution is kept into it? (b) What qualities are exhibited by Mohan?
question_answer57) A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas C causes global warming. (a) Identify A, B and C (b) To which group of periodic table does A belong?
question_answer58) Name the following (a) A metal which is preserved in kerosene. (b) A lustrous coloured non-metal. (c) A metal which can melt while kept on palm. (d) A metal which is a poor conductor of heat.
question_answer59) Name a metal which (a) is the best conductor of heat. (b) has a very low melting point. (c) does not react with oxygen even at high temperature. (d) is most ductile.
question_answer60) Give reason for the following (a) School bells are made up of metals. (b) Electrical wires are made up of copper.
question_answer61) State four general properties of ionic compounds.
question_answer62) An element E combines with to form an oxide , which is a good conductor of electricity. Answer the following (a) How many electrons will be present in the outer most shell of E? (b) Write the formula of the compound formed when it combines with chlorine.
question_answer63) An element X on reaction with forms This oxide dissolves in water and turns blue litmus paper red. Predict the nature of the metal or a non-metal.
question_answer64) Royal water is prepared by mixing two acids A and B. It can dissolve gold and platinum. It is highly corrosive and fuming liquid. Identify A and B. What is the ratio in which A and B are mixed?
question_answer65) Why sodium chloride has high melting point?
question_answer66) Why is that sodium when react with water form sodium hydroxide whereas aluminium form only aluminium oxide?
question_answer67) Name an alloy (a) which has lower melting point than its constituents. (b) which is more hard, tough and strong than its constituents.
question_answer68) Name any one alloy made with (a) a metal and a non-metal (b) two metals
question_answer69) Alloys are used in electrically heating devices rather than pure metals. Give reasons.
question_answer70) State which of the following chemical reactions will take place or not, giving suitable reason for each? (a) (b) (c)
question_answer71) An ore on heating in air produces sulphur dioxide. (a) Which process would you suggest for its concentration? (b) Describe briefly any two steps involved in the conversion of this concentrated ore into related metal.
question_answer72) Give reasons for the following observations (a) Ionic compounds in general have high melting and boiling points. (b) Highly reactive metals cannot be obtained from their oxides by heating them with carbon. (c) Copper vessels get a green coat when left exposed to air in the rainy season.
question_answer73) 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.
question_answer74) A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black coloured product. Identify M and black coloured product and also explain the reaction of remove overlap.
question_answer75) Two ores A and B were taken. On heating, ore A gives whereas ore B gives . What steps will you take to convert them into metals?
question_answer76) of the three metals X, Y and Z, X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity.
question_answer77) Give an example of a metal which (a) is both malleable and ductile (b) is best conductor of heat (c) is a poor conductor of heat
question_answer78) (a) Write the name of the products formed when zinc reacts with NaOH. (b) Also write the balanced chemical equation for the reaction involved. (c) Write a test to confirm the presence of the gas evolved during this reaction.
question_answer79) Explain the reactions of different metals with hot water, cold water and steam. Give one example with a proper balanced chemical equation. Name two metals which do not react with any form of water.
question_answer80) State the reason why? (a) Metals replace hydrogen from acids whereas non-metals do not. (b) Calcium does not occur free in nature. (c) Zinc is used in the galvanisation of iron and not the copper.
question_answer81) (a) Write the electron dot structures for calcium and oxygen. The atomic numbers of calcium and oxygen are 20 and 8 respectively. (b) Show the formation of calcium oxide by the transfer of electrons.
question_answer82) Show the formation of MgO by the transfer of electrons in the two elements using electron-dot structures. Or Atomic number of Mg is 12 and of oxygen is 8. Show the formation of MgO from its elements. Or Using the electronic configurations, explain how magnesium atom combines with oxygen atom to form magnesium oxide by transfer of electrons.
question_answer83) A, B and C are 3 elements which undergo chemical reactions according to following equations (i) (ii) (iii) Answer the following (a) Which element is most reactive? (b) Which element is least reactive?
question_answer84) A student was given Mg, Zn, Fe and Cu metals. He put each of them in dilute HCl contained in different test tubes. Identify which of them (a) will not displace H^ from dilute HCl. (b) will give H, with 5% . (c) will be displaced from its salt solution by all other metals.
question_answer85) A yellow coloured powder X is soluble in carbon disulphide. It burns with a blue flame forming suffocating smelling gas which turns moist blue litmus red. Identify X and give chemical reaction. Identify it is metal or non-metal.
question_answer86) A metal acts as a good reducing agent. It reduces and . The reaction with is used for welding broken railway tracks. Identify the metal and write all the chemical reactions.
question_answer87) Mercury is the only metal found in the liquid state. It is largely used in thermometers to measure the temperature, but mercury is a very dangerous metal as its density is very high. What two precautions you would take while handling the equipments containing mercury? What will learners infer from this?
question_answer88) Hydrogen is not a metal but it has been assigned a place in the reactivity series of metals. Explain.
question_answer89) Corrosion is a serious problem. Every year an enormous amount of money is spend to replace damaged iron. What steps can be taken to prevent this damage? What will learners infer from this passage?
question_answer90) Why is titanium called a strategic metal? Mention two of its properties which make it so special.
question_answer91) Gold is a very precious metal. Pure gold is very soft it is therefore not suitable for making jewellery. It is alloyed with either silver or copper to make it hard. But sometimes jewellers mix a large quantity of copper and silver in gold to earn more profit. Read the above passage and answer the following questions (a) What precautions should you take while purchasing gold jewellery? (b) Why does government insist onpurchasing hall marked jewellery? (c) What value is associated with the given passage?
question_answer92) No reaction takes place when granules of a solid A are mixed with a powder of solid B. However when the mixture is heated, a reaction starts with evolution of much heat and produce liquid C and solid D. This reaction is sometimes used for making metals for ready use in odd places. (a) Based on this information, make assumptions about A and B and corresponding deductions about C and D and write a balanced chemical equation for the reaction. Include in the equation chemical equation about physical states of the reactants and products, need of heating for starting the reaction being exothermic. (b) Name two types of chemical reactions to which this reaction can belong.
question_answer93) Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below. (a) What will be the action of gas on (i) dry litmus paper (ii) moist litmus paper? (b) Write a balanced chemical equation for the reaction taking place.
question_answer94) What are alloys? How are they made? Name the constituents and uses of brass, bronze and solder.
question_answer95) With the help of a suitable example, explain how ionic compounds are formed. State any three general properties of ionic compounds.
question_answer96) Choose from the following metals to answer the questions below aluminium, calcium, copper, iron, magnesium, potassium, nickel, zinc. Each metal can be used once, more than once or not at all. Name a metal which (a) is manufactured by the electrolysis of its molten oxide. (b) is used to galvanise iron. (c) is alloyed with zinc to make brass (d) reacts with aqueous copper (II) sulphate to give a pink solid. (e) does not react with cold water.
question_answer97) Explain the following (a)Reactivity of Al decreases if it is dipped in. (b) Carbon cannot reduce the oxides of Na or Mg. (c) NaCI is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state. (d) Iron articles are galvanised. (e) Metals like Na, K, Ca and Mg are never found in their free state in nature.
question_answer98) Given below are the steps for extraction of copper from its ore. Write the reaction involved. (i) Roasting of copper (I) sulphide. (ii) Reduction of copper (I) oxide with copper (I) sulphide. (iii) Electrolytic refining. (b) Draw a neat and well labelled diagram for electrolytic refining of copper.
question_answer99) (a) Predict the reaction, if any, between (i) zinc and silver nitrate solution, (ii) magnesium and iron (II) chloride solution, (iii) copper and magnesium sulphate solution. Write the equations, with state symbols, for the reaction. (b) A lump of element X can be cut by a knife. During its reaction with water, X floats and melts. What is X? Explain.
question_answer100) Shashi bought new silver anklets. After a month she found that the anklets turns black. She has doubt that it is not of pure silver but her neighbour Rakhi advised her that it is of pure silver and wash it with tamarind or lemon juice to get the luster back. She followed the advise and get the lustre of her anklet back. Answer the following questions based on the above passage. (a) Do you think that the anklets are not of pure silver? (b) Why these turn black after sometime? (c) Why the anklets become lustrous on washing with tamarind or lemon juice? (d) What values are exhibited by Rakhi?
question_answer101) In what forms are metals found in nature? With the help of examples explain how metals react with oxygen, water and dilute acids. Also write chemical equations for the reactions.
question_answer102) Four metals A, B, C and D are added to the following solutions one by one. The observations made are tabulated below. Metal Iron (II) sulphate Copper (II) sulphate Zinc sulphate Silver nitrate A No reaction Displacement - - B Displacement - - - C No reaction No reaction No reaction Displacement D No reaction No reaction No reaction No reaction Answer the following questions based on the above information (a) Which is the most active metal and why? (b) What would be observed if B is added to a solution of copper sulphate and why? (c) Arrange the metals A, B, C and D in order of increasing reactivity. (d) Container of which metal can be used to store both zinc sulphate solution and silver nitrate solution? (e) Which of the above solutions can be easily stored in a container made up of any of these metals?
question_answer103) (a) Aluminium oxide is amphoteric oxide (b) Metal displace hydrogen gas from acids (c) Iron articles are frequently painted (d) Iron sheets are coated with zinc layer (e) Lemon or tamarind juice are effective in cleaning tarnished copper vessels.
question_answer104) (a) Distinguish between 'roasting' and 'calcination'. "Which of these two is used for sulphide ores and why? (b) Write a chemical equation to illustrate the use of aluminium for joining cracked railway lines. (c) Name the anode, the cathode and the electrolyte used in the electrolytic refining of impure copper.
question_answer105) (a) Distinguish between ionic and covalent compounds under the following properties. (i) Strength of forces between constituent elements. (ii) Solubility of compounds in water. (iii) Electrical conduction in substances. (b) Explain how the following metals are obtained from their compounds by the reduction process. (i)Metal M which is in the middle of the reactivity series. (ii) Metal N which is high up in the reactivity series. Give one example of each type.
question_answer106) Write balanced chemical equation for the reaction taking place when (a) Zinc carbonate is calcinated. (b) Zinc sulphide is roasted. (c) Zinc oxide is reduced in the zinc. (d) Cinnabar is heated in the air. (e) Manganese dioxide is heated with aluminium powder.
question_answer107) The way by which metals like sodium, magnesium and iron react with air and water is an indication of their relative positions in the 'reactivity series'? Is this statement true? Justify your answer with examples.
question_answer108) Differentiate between metal and non-metal on the basis of their chemical properties.
question_answer109) Why are metals good conductors of electricity?
question_answer110) Which property of graphite is utilized in making electrodes?
question_answer111) Which of the following metals will melt at body temperature? Gallium, Magnesium, Caesium, Aluminium [CBSE Delhi 2008C]
question_answer112) Name two metals that do not react with water at all.
question_answer113) Name two metals which will displace hydrogen from dilute acids, and two metals which will not. [NCERT]
question_answer114) What happens when calcium is treated with water?
question_answer115) Generally, non-metals are not lustrous. Name a non-metal which is lustrous.
question_answer116) What are amphoteric oxides? Give two examples of amphoteric oxides. [NCERT, CBSE (AI) 2008]
question_answer117) What is the nature of non-metal oxide?
question_answer118) What is the nature of metal oxides?
question_answer119) Why do copper objects develop a green coating in air?
question_answer120) Why do silver articles become black on prolonged exposure to air?
question_answer121) Which oxide of iron could be obtained on prolonged reaction of iron with steam?
question_answer122) Why do ionic compounds have high melting points? [NCERT, CBSE (AI) 2008C]
question_answer123) Why are ionic compounds usually hard? [CBSE Delhi 2008]
question_answer124) Why does aluminium not react with water under ordinary conditions?
question_answer125) In nature, metal A is found in a free state while metal B is found in the form of its compounds. Which of these two will be nearer to the top of the activity series of metals?
question_answer126) Arrange the following metals in decreasing order of their reactivity: Fe, Zn, Na, Cu, Ag [CBSE (AI) 2008C]
question_answer127) Why cannot aluminium be obtained by reduction of its oxide with carbon?
question_answer128) Why does a little addition of carbon in iron make it more useful?
question_answer129) Give an example of a sulphide ore which is reduced to metal by heating alone, i.e., by roasting.
question_answer130) Metals are refined by using different methods. Name two metals refined by electrolytic refining.
question_answer131) What is rust?
question_answer132) What is corrosion?
question_answer133) What is aqua regia?
question_answer134) What are alloys? [NCERT]
question_answer135) Which metals are mixed with iron to get stainless steel?
question_answer136) Why is stainless steel preferred for making household utensils?
question_answer137) What is galvanization?
question_answer138) Name an alloy of (i) aluminium used in the construction of aircraft. (ii) lead used in joining metals for electrical work.
question_answer139) Give an example of a metal which (i) is a liquid at room temperature; (ii) can be easily cut with a knife; (iii) is the best conductor of heat; (iv) is a poor conductor of heat; (v) found in free state in nature; (vi) occurs in free state as well as in combined state. [NCERT]
question_answer140) Why is sodium kept immersed in kerosene oil? [NCERT]
question_answer141) Explain why the surface of some metals acquires a dull appearance when exposed to air for a long time.
question_answer142) Name two metals which react violently with cold water. Write any observation you would make when such a metal is dropped into water. How would you identify the gas evolved, if any, during the reactions? [CBSE (AI) 2008]
question_answer143) Write equations for the reactions of (i) iron with steam. (ii) calcium and potassium with water. [NCERT]
question_answer144) Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4. [NCERT]
question_answer145) Give reasons: (i) Reactivity of Al decreases if it is dipped in HNO3 [NCERT Exemplar] (ii)Carbon cannot reduce the oxides of Na or Mg. (iii) Nad is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state. (iv) Metals like Na, K, Ca and Mg are never found in their free state in nature.
question_answer146) Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it as shown in figure. What will be the action of gas on (i) dry litmus paper? (ii) moist litmus paper? (b) Write a balanced chemical equation for the reaction taking place. [NCERT]
question_answer147) Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows: Metal Iron(II) sulphate Copper(II) sulphate Zinc sulphate Silver nitrate A B C D No reaction Displacement No reaction No reaction Displacement ? No reaction No reaction - No reaction No reaction No reaction - - Displacement No reaction Use the table above to answer the following questions about metals A, B, C and D. (a) Which is the most reactive metal? (b) What would you observe if B is added to a solution of copper(ii) sulphate? (c)Arrange the metals A, B, C and D in the order of decreasing reactivity. [NCERT]
question_answer148) What would you observe when zinc is added to a solution of iron (II) sulphate? Write the chemical reaction that takes place. [NCERT]
question_answer149) A zinc plate was kept in a glass container having copper sulphate solution. On examining it was found that the blue colour of the solution is getting fader and fader. After a few days when the zinc plate was taken out of the solution, a number of small holes were noticed in it. State the reason and give chemical equation of the reaction involved.
question_answer150) Metals replace hydrogen from dilute acids, whereas non-metals do not. Why? [CBSE (AI) 2008]
question_answer151) What happens when (chemical equation only) (i) iron nail is placed in silver nitrate solution? (ii) iron strip is dipped in zinc sulphate solution?
question_answer152) Why do metals not evolve hydrogen gas with nitric acid? [CBSE Delhi 2008C]
question_answer153) (i) Name a metal for each case: (a) It does not react with cold as well as hot water but reacts with steam. (b) It does not react with any physical state of water. (ii) When calcium metal is added to water the gas evolved does not catch fire but the same gas evolved on adding sodium metal to water catches fire. Why is it so? [CBSE (AI) 2008]
question_answer154) When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved. [NCERT Exemplar]
question_answer155) Which of the following reactions will not occur? Give reasons. (i) MgS04(aq) +Fe(s) FeSO4aq) + Mg(s) (ii) MgSO4(aq)+Cu(s) CuSO4(aq) + Mg(s) (iii) CuSO4(aq) + Fe(s) FeSO4(aq) + Cu(s)
question_answer156) Of the three metals X, Y and Z, X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity. [NCERT Exemplar]
question_answer157) State the reason for the following behaviour of zinc metal: On placing a piece of zinc metal in a solution of mercuric chloride, it acquires a shining silvery surface but when it is placed in a solution of magnesium sulphate no change is observed.
question_answer158) An element A bums with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved. [NCERT Exemplar]
question_answer159) Define the terms: (a) Mineral (b) Ore (c) Gangue. [NCERT, CBSE (AI) 2006]
question_answer160) Give the difference between electrolytic reduction and reduction with carbon.
question_answer161) What is meant by refining of metals? Describe the electrolytic refining of copper with a neat labelled diagram. [CBSE Delhi 2009]
question_answer162) An ore gives carbon dioxide on treatment with a dilute acid. What steps will you take to convert such a concentrated ore into free metal?
question_answer163) ore on heating in air produces sulphur dioxide. Which process would you suggest for its concentration? Describe briefly any two steps involved in the conversion of this concentrated ore into related metal. [CBSE Delhi 2009]
question_answer164) During extraction of metals, electrolytic refining is used to obtain pure metals. (i) Which material will be used as anode and cathode for refining of silver metal by this process? (ii) Suggest a suitable electrolyte also. (iii) In this electrolytic cell, where do we get pure silver after passing electric current?
question_answer165) What is a thermit reaction? State one use of this reaction.
question_answer166) A metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved. [NCERT Exemplar]
question_answer167) What is 24-carat gold? How will you convert it into 18-carat gold?
question_answer168) A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
question_answer169) What would happen to iron railings on the road side if they are not painted? Why does it happen so?
question_answer170) Explain why, the galvanized iron article is protected against rusting even if the zinc layer is broken.
question_answer171) How can a layer of aluminium oxide on an aluminium object be made thicker? What is this process called?
question_answer172) (i) A metal M is found in nature as MC03. It is used in galvanizing iron articles. Name the metal. (ii) How can the metal be obtained from its carbonate ore?
question_answer173) Which two metals do not corrode easily? Give an example in each case to support that (i) corrosion of some metals is an advantage. (ii) corrosion of some metals is a serious problem.
question_answer174) Why is aluminium oxide considered an amphoteric oxide? [CBSE Delhi 2008C]
question_answer175) A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas C causes global warming. (a) Identify A, B and C. (b)To which group of Periodic Table does A belong?
question_answer176) Why are food cans tin-plated instead of zinc plated though zinc is cheaper than tin?
question_answer177) In the formation of the compound XY, atoms of X lost one electron each while atoms of Y gained one electron each. What is the nature of bond in XY? Predict the two properties of XY.
question_answer178) Why do ionic compounds conduct electricity in molten state? [CBSE Delhi 2008C]
question_answer179) (i) Write the electron-dot structures for sodium, oxygen and magnesium. (ii) Show the formation of Na2O and MgO by the transfer of electrons. What are the ions present in these compounds?
question_answer180) Give reasons: (a) Platinum, gold and silver are used to make jewellery. (b) Sodium, potassium and lithium are stored under oil. (c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking. (d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction. (e) Lemon or tamarind juice are effective in cleaning tarnished copper vessels. [CBSE Delhi 2008C]
question_answer181) (i) Hydrogen is not a metal but it has been assigned a place in the reactivity series of metals. Explain. (ii) How would you show that silver is chemically less reactive than copper?
question_answer182) (i) What is an ionic bond? (ii) How is an ionic bond formed? (iii) Write the formation of magnesium chloride.
question_answer183) Distinguish between ionic and covalent compounds under the following properties: (a) Strength of forces between constituent elements (b) Solubility of compounds in water (c) Electrical conduction in substances (ii) Explain how the following metals are obtained from their compounds by the reduction process: (a) Metal M which is in the middle of the reactivity series (b) Metal N which is high up in the reactivity series Give one example of each type. [CBSE (AI) 2009]
question_answer184) (i) Distinguish between 'roasting' and 'calcination'. Which of these two is used for sulphide ores and why? (ii) Write a chemical equation to illustrate the use of aluminium for joining cracked railway lines. (iii) Name the anode, the cathode and the electrolyte used in the electrolytic refining of impure copper. [CBSE (At) 2009]
question_answer185) Write about different chemical processes used for obtaining a metal from its oxides, for metals low in the reactivity series, metals in the middle of reactivity series and metals towards the top of the reactivity series.
question_answer186) (i) How do you classify elements into metals and non-metals on the basis of their electronic configuration? Choose metal and non-metal out of the following: (ii) What type of bond will be formed if (a) 'A' combines with 'B'? (b) 'A' combines with 'E'? (c) 'C' combines with 'E'? (d) 'D' combines with 'E'?
question_answer187) There are 3 unknown metals ? A, B and C. C displaces B from its oxide while with oxide of A, there is no reaction. Give the reactivity order of A, B and C.
question_answer188) A copper coin is kept immersed in a solution of silver nitrate for some time. What will happen to the coin and the colour of solution?
question_answer189) An element A reacts with water to form a compound B which is used in white-washing. The compound B on heating forms an oxide C which on treatment with water gives back B. Identify A, B and C and give the reactions involved. [NCERT Exemplar]
question_answer190) 'M' is an element which is out of Cu, Fe, Al, Na. It shows the following properties: (i) One of its ore is rich in M2O3. (ii) M2O3 is not affected by water. (iii) It corrodes easily. (iv) It forms two chlorides MCl2 and MCl3. Identify 'M'.
question_answer191) Carbon can reduce copper oxide to copper but not CaO to Ca. Why?
question_answer192) A metal A, which is used in thermit process, when heated with oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCl and NaOH. [NCERT Exemplar]
question_answer193) An ore on treatment with dilute hydrochloric acid gives a smell like that of rotten eggs. What type of ore is this? How can it be concentrated? How can the metal be obtained from the concentrated ore?
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