{"id":644,"date":"2016-02-29T14:46:00","date_gmt":"2016-02-29T09:16:00","guid":{"rendered":""},"modified":"2020-08-01T01:26:56","modified_gmt":"2020-07-31T19:56:56","slug":"textbook-answers-and-solutions-of-cbse-class-viii-science-chapter-4-materials-metals-and-non-metals","status":"publish","type":"post","link":"https:\/\/cbsencertanswers.com\/2016\/02\/textbook-answers-and-solutions-of-cbse-class-viii-science-chapter-4-materials-metals-and-non-metals.html","title":{"rendered":"TEXTBOOK ANSWERS AND SOLUTIONS OF CBSE CLASS VIII SCIENCE Chapter 4 MATERIALS:METALS AND NON METALS"},"content":{"rendered":"
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\n
<\/span><\/u><\/b>
\nExercises<\/span><\/u><\/b><\/o:p><\/span><\/u><\/b><\/div>\n

\n<\/div>\n
\n1) Which of the following can be beaten into thin sheets?<\/o:p><\/span><\/i><\/b><\/div>\n
\n(a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen<\/o:p><\/span><\/i><\/b><\/div>\n
\n<\/div>\n
\nANSWER \ud83d\ude41<\/span> a) Zinc<\/o:p><\/span><\/div>\n
\n<\/div>\n
\n2) Which of the following statements is correct?<\/o:p><\/span><\/i><\/b><\/div>\n
\n(a) All metals are ductile.<\/o:p><\/span><\/i><\/b><\/div>\n
\n(b) All non-metals are ductile.<\/o:p><\/span><\/i><\/b><\/div>\n
\n(c) Generally, metals are ductile.<\/o:p><\/span><\/i><\/b><\/div>\n
\n(d) Some non-metals are ductile.<\/o:p><\/span><\/i><\/b><\/div>\n
\n<\/div>\n
\nANSWER:-<\/span>c) Generally, metals are<\/span> ductile<\/o:p><\/span><\/div>\n
\n<\/div>\n
\n3) Fill in the blanks:<\/o:p><\/span><\/i><\/b><\/div>\n
\n(a) Phosphorus is a very __reactive__ non-metal.<\/span><\/o:p><\/span><\/div>\n
\n(b) Metals are __good__ conductors of heat and__electricity__.<\/span><\/o:p><\/span><\/div>\n
\n(c) Iron is __more__ reactive than copper.<\/span><\/o:p><\/span><\/div>\n
\n(d) Metals react with acids to produce __hydrogen__ gas.<\/span><\/o:p><\/span><\/div>\n
\n<\/div>\n
\n4) Mark \u2018T\u2019 if the statement is true and \u2018F\u2019 if it is false.<\/o:p><\/span><\/i><\/b><\/div>\n
\n(a) Generally, non-metals react with acids. ( )<\/o:p><\/span><\/i><\/b><\/div>\n
\n(b) Sodium is a very reactive metal. ( )<\/o:p><\/span><\/i><\/b><\/div>\n
\n(c) Copper displaces zinc from zinc sulphate solution. ( )<\/o:p><\/span><\/i><\/b><\/div>\n
\n(d) Coal can be drawn into wires. ( )<\/o:p><\/span><\/i><\/b><\/div>\n
\n<\/div>\n
\nANSWER:-<\/span> <\/o:p><\/span><\/div>\n
\na)F<\/o:p><\/span><\/div>\n
\nb)T<\/o:p><\/span><\/div>\n
\nc)F<\/o:p><\/span><\/div>\n
\nd)F<\/o:p><\/span><\/div>\n
\n<\/div>\n
\n5) Some properties are listed in the following Table. Distinguish
\nbetween metals and non-metals on the basis of these properties.<\/o:p><\/span><\/i><\/b><\/div>\n
\n
<\/span><\/i><\/b><\/div>\n
\nProperties.                                       Metals Non-metal<\/o:p><\/span><\/i><\/b><\/div>\n
\n
<\/span><\/i><\/b><\/div>\n
\n1. Appearance<\/o:p><\/span><\/i><\/b><\/div>\n
\n2. Hardness<\/o:p><\/span><\/i><\/b><\/div>\n
\n3. Malleability<\/o:p><\/span><\/i><\/b><\/div>\n
\n4. Ductility<\/o:p><\/span><\/i><\/b><\/div>\n
\n5. Heat<\/o:p><\/span><\/i><\/b><\/div>\n
\nConduction<\/o:p><\/span><\/i><\/b><\/div>\n
\n6. Conduction of Electricity<\/o:p><\/span><\/i><\/b><\/div>\n
\n<\/div>\n
\nANSWER:-<\/span><\/o:p><\/span><\/div>\n
\nMetals<\/span><\/b>-Lustrous, hard, Can be<\/span> beaten into thin sheets; Can be beaten into wires, Good
\nconductors of heat, Good conductors of electricity.<\/o:p><\/span><\/div>\n
\n<\/div>\n
\nNon-Metals<\/span><\/b>-dull, soft, Cannot be<\/span> beaten into thin sheets, Cannot be beaten into wires, Poor
\nconductors of heat, Poor conductors of electricity.<\/o:p><\/span><\/div>\n
\n<\/div>\n
\n6) Give reasons for the following.<\/o:p><\/span><\/i><\/b><\/div>\n
\n(a) Aluminium foils are used to wrap food items.<\/o:p><\/span><\/i><\/b><\/div>\n
\n(b) Immersion rods for heating liquids are made up of metallic
\nsubstances.<\/o:p><\/span><\/i><\/b><\/div>\n
\n(c) Copper cannot displace zinc from its salt solution.<\/o:p><\/span><\/i><\/b><\/div>\n
\n(d) Sodium and potassium are stored in kerosene<\/o:p><\/span><\/i><\/b><\/div>\n
\n<\/div>\n
\nANSWER \ud83d\ude41<\/span>a) Aluminium foils are<\/span> used to wrap food items because aluminium metal is
\nmalleable. Therefore, it can be beaten into thin foils.<\/o:p><\/span><\/div>\n
\n
<\/span><\/div>\n
\n(b) Metals are good conductors of heat and electricity. Therefore,<\/span>
\nimmersion rods for heating liquids are made of metallic substances.<\/o:p><\/span><\/div>\n
\n
<\/span><\/div>\n
\n(c) A metal can displace a less reactive metal from its salt in an
\naqueous solution. But zinc is more reactive than copper. Therefore,<\/span>
\ncopper cannot displace zinc from its salt solution.<\/o:p><\/span><\/div>\n
\n
<\/span><\/div>\n
\nd) Sodium and potassium are stored in kerosene because they are
\nhighly reactive elements. They can easily catch fire even<\/span>
\nwhen in contact with air.<\/o:p><\/span><\/div>\n
\n
<\/span><\/div>\n
\n7) Can you store lemon pickle in an aluminium utensil? Explain.<\/o:p><\/span><\/i><\/b><\/div>\n
\n<\/div>\n
\nANSWER:-<\/span>Lemon pickle cannot be<\/span> stored in aluminium utensils because lemon pickle contains
\nacids, which can react with aluminium (metal)
\nliberating hydrogen gas. This can lead to the spoiling
\nof the pickle.<\/o:p><\/span><\/div>\n
\n<\/div>\n
\n8) Match the substances given in Column A with their uses given
\nin Column B.<\/o:p><\/span><\/i><\/b><\/div>\n
\nA                                                                 B<\/o:p><\/span><\/i><\/b><\/div>\n
\n(i) Gold                                      (a) Thermometers<\/o:p><\/span><\/i><\/b><\/div>\n
\n(ii) Iron                                     (b) Electric wire<\/o:p><\/span><\/i><\/b><\/div>\n
\n(iii) Aluminium.                        (c)
\nWrapping food<\/o:p><\/span><\/i><\/b><\/div>\n
\n(iv) Carbon                                (d) Jewellery<\/o:p><\/span><\/i><\/b><\/div>\n
\n(v) Copper                                 (e) Machinery<\/o:p><\/span><\/i><\/b><\/div>\n
\n(vi) Mercury                               (f) Fuel<\/o:p><\/span><\/i><\/b><\/div>\n
\n<\/div>\n
\nANSWER:-<\/span><\/o:p><\/span><\/div>\n
\nA.                                                      B<\/span><\/b><\/o:p><\/span><\/b><\/div>\n
\n(i) Gold                                     d)
\nJewellery<\/span><\/o:p><\/span><\/div>\n
\n(ii) Iron                     
\n               e) Machinery<\/span><\/o:p><\/span><\/div>\n
\n(iii) Aluminium.                         c) Wrapping food<\/span><\/o:p><\/span><\/div>\n
\n(iv) Carbon                               f)
\nFuel<\/span><\/o:p><\/span><\/div>\n
\n(v) Copper                                b) Electric wire<\/span><\/o:p><\/span><\/div>\n
\n(vi) Mercury                             a) Thermometers<\/span><\/o:p><\/span><\/div>\n
\n<\/div>\n
\n9) What happens when?<\/o:p><\/span><\/i><\/b><\/div>\n
\n(a) Dilute sulphuric acid is poured on a copper plate?<\/o:p><\/span><\/i><\/b><\/div>\n
\n(b) Iron nails are placed in copper sulphate solution? <\/o:p><\/span><\/i><\/b><\/div>\n
\nWrite word equations of the reactions involved.<\/o:p><\/span><\/i><\/b>
\n
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\n<\/p>\n
\n<\/div>\n


<\/span><\/i><\/b><\/div>\n

\n<\/div>\n
\nANSWER<\/span>:-a) When dilute sulphuric acid is poured on a copper plate, the
\ncopper metal reacts with sulphuric acid to liberate hydrogen gas.<\/span><\/o:p><\/span><\/div>\n
\n
<\/span><\/div>\n
\n(b) Iron being more reactive displaces copper from copper sulphate
\nsolution. In this reaction, the blue colour of copper sulphate fades and there
\nis deposition of copper on the iron nail.<\/span><\/o:p><\/span><\/div>\n
\n<\/div>\n
\n10) Saloni took a piece of burning charcoal and collected the
\ngas evolved in a test tube.<\/o:p><\/span><\/i><\/b><\/div>\n
\n(a) How will she find the nature of the gas?<\/o:p><\/span><\/i><\/b><\/div>\n
\n(b) Write down word equations of all the reactions taking place
\nin this process.<\/o:p><\/span><\/i><\/b><\/div>\n
\n<\/div>\n
\nANSWER<\/span> \ud83d\ude41 a) Add a few drops of<\/span> water in the test tube containing gas. Now, cover the test
\ntube and shake it well. After shaking, test the solution with blue litmus
\nand red litmus. It will turn blue litmus red. Thus,
\nthe gas is acidic in nature.<\/o:p><\/span><\/div>\n
\n
<\/span><\/div>\n
\n(b) Charcoal reacts with oxygen to form carbon dioxide gas. Carbon
\ndioxide reacts with water to form carbonic acid, which turns blue litmus paper
\nred.<\/span><\/o:p><\/span><\/div>\n

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