Why not? Conduction of electrical - good conductor ( metals) - bad conductor (non metals), Q.6 Give reasons for the following. Your email address will not be published. (c) Copper cannot displace zinc from its salt solution. Name two metals which are soft and can be easily cut with a knife. If a piece of zinc metal is added to aluminium sulphate solution, no reaction takes place. Then drop in the nail. Iron is used in construction of bridges and houses. Q.9 What happens when ( ) (d) Coal can be drawn into wires. FeSO 4 (aq) + Zn (s) → ZnSO 4 (aq) + Fe (s). (ii) Iron (iii) in oxy-hydrogen flame for cutting and welding metals. What is the zinc In the sample provided?_____ How many moles of zinc are In this sample? [NCERT] They are also sometimes made by mixing metal powders together. Question 14.State whether the following statements are True or False : 1. True. 4. However, its reactions with oxygen and water seem to indicate that it is less reactive than iron. Zinc sulphate and magnesium Sodium is a very reactive metal. Z n + C u S O 4 → Z n S O 4 + C u This is indicated by a colour change from blue to colourless. (adsbygoogle = window.adsbygoogle || []).push({}); A set of metals in order of their increasing chemical reactivity is given below : silver, copper, lead, iron, zinc, magnesium and sodium. (d) Coal can be drawn into wires. But all metals do not react in the same way with water. Then repeat the same kind of treatment on the coal piece and pencil lead. Noble metals – Gold, silver and platinum are noble metals. Ans. Making pencil leads: – Graphite 6. 2. The activity shows that for rusting to take place, both air (oxygen) and water are essential. The electrodes are connected to a DC power supply and a voltage is applied - the negative lead on the copper electrode and the positive lead on the zinc … Mark ‘T’ if the statement is true and ‘F’ if it is false. So aluminium is more reactive than zinc. Non-metals are generally (malleable/brittle). Would it still have been such a useful metal .Give reason? (ii) Electroplating: Tin is electroplated on iron to make food containers commonly called tin cans. This is indicated by colour change from blue to colourless. Coal can be drawn into wires. Q.11 One day Reeta went to a jeweller’s shop with her mother. (f) Fuel, A ( ) (c) Copper displaces zinc from zinc sulphate solution. [ ] (d) Coal can be drawn into wires. They occur free in nature . If you are an engineer constructing a multi storey building, which alloy would you be extensively using and why? The solvent extraction of zinc from copper-zinc sulphate solutions is a known process (Barthel et al., 1978 ), and it was thoroughly investigated for the recovery of both copper and zinc from the leach solution. Sodium and potassium are stored in kerosene. 4. (a) Diamond(b) Graph’ite(c) Fullerenes(d) CharcoalAnswer:(c), Question 11.Which among the following alloys contain mercury as one of its constituents? Silver is lower in the reactivity series than Zinc and therfore cannot displace the Sulphate from the Zinc. T. 3. Why are musical instrument and bell made up of metal? Give the names and composition of alloys that are used for the following. Why sodium and potassium stored in kerosene? Zinc is a nutrient that plays many vital roles in your body. 4. Which of the following statements is true about the reaction between zinc and copper sulfate? Beaker A: Copper sulphate (CuSO4) + Zinc granule (Zn), Beaker B: Copper sulphate (CuSO4) + Iron nail (Fe). What can be the reason for this? Question 15.From among the set of metals — sodium, zinc, iron, copper, silver, select the following giving equations for each reaction :(a) Two metals which will liberate hydrogen from water. Also write the equation of the reaction. 2Cu + O2 → 2CuO; 4Al + 3O2 → 2Al2O3. (c) Zinc sulphate and copper: A displacement reaction will not occur here because copper is placed below zinc. copper sulphate and ironc. (c) Copper displaces zinc from zinc sulphate solution. ( ) Answer: 1. F. 4. What mass of ice, at 0.00 ° C, can be converted to steam, at 100. d) False, Some properties are listed in the following table. [ ] (c) Copper displaces zinc from zinc sulphate solution. Ans: Aqua regia, (Latin for ‘royal water’) is a mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1. 10. (e) Machinery Give three examples of reactions between metals and water, to show that different metals have different relativities. Nothing will happen as copper does not react with hydrochloric acid. Malleability - Can be beaten into thin Zinc pieces will dissolve in CuSO 4 solution and the intensity of the blue colour of CuSO 4 solution decreases. (a) All metals are ductile. To avoid this they are stored in kerosene. Question 4: Mark ‘T’ if the statement is true and ‘F’ if it is false. ( ) (b) Sodium is a very reactive metal. ( ) 8. ( ) NCERT SOLUTIONS CLASS VIII SCIENCE CHAPTER-4 … (b) Covering with another metal: Depositing a layer of another metal which is more resistant to corrosion is another commonly used method. thin sheets used for wrapping of food items, medicines, etc. Copper displaces zinc from zinc sulphate solution. (F) (iv) Coal can be drawn into wires. Noble gases are found in (free state/compound forms). ( ), Copper displaces zinc from zinc sulphate solution. (a) Phosphorus is a very _________non-metal. Discuss why it is necessary to anodize aluminum to make it corrosion resistant. Making foil for wrapping food: – Aluminium5. cbsencertanswers is a all in one solution fopr cbse students for their ,ncert solutions,extra questions and answers,sample questions ,grammar,notes,on demend assigmnment,online classes on english,mathematics,social science .science,bengali, computer etc. As HNO3 is a strong oxidizing agent, it oxidizes the H2 to water and itself gets reduced to oxide of nitrogen (N2O, NO, NO2).Magnesium and Manganese react with very dil.HNO3 to give H2 gas.Mg(s) + 2HNO3 (aq) → Mg(NO3)2 + H2 ; Mn (s) + 2HNO3(aq) → Mn(NO3)2 + H2. When it is red hot, it reacts with steam. Zinc is more reactive than copper… 4. Write the equation also. 1:12 25.2k LIKES Q.2 Which of the following statements is correct? (iii) Aluminium Sodium is a very reactive metal. It is used in the manufacture of sulphuric acid. Lower the value of reduction potential more easily is the substance oxidised and greater the value of reduction potential, more easily is the substance reduced. Answer: (a) False (b) True (c) False (d) False. 25.2k LIKES 7.7k VIEWS Coal can be drawn into wires. When iron nails are placed in copper sulphate solution, iron sulphate and copper are formed. (a) Generally, non-metals react with acids. Aluminium is a highly malleable metal and can be made into foils. Prediction I predict that this experiment should be a displacement reaction. Ans. Q3. As a result zinc sulphate is formed. (a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen. Therefore, it cannot displace zinc from its salt solution. Constructing bridge: – Iron3. Close this test tube also with a cork. Zinc displaces copper from copper(II) sulphate solution. (a) Thermometers Ans: An alloy is a mixture of two or more metals or one or more metals and a non-metal. zinc sulfate solution. (vi) Mercury ( ) (ii)Coal can be drawn into wires. E. LONG-ANSWER QUESTIONS: Answer in about 60 words. Ans: Different methods are used for preventing corrosion of metals. German silver has (copper/silver) as major constituent. ( ) Answer-(i) Sodium is a very reactive metal. List three important uses of hydrogen. Zinc replaces copper in copper sulphate, because it is more reactive. Write word equations of the reactions involved. Copper sulfate is highly soluble in water, with solubility values of 1.055 molal and 1.502 molal ate 10 o C and 30 o C respectively. 1. The heat evolved is not sufficient for the hydrogen to catch fire.Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g)Calcium starts floating because the bubbles of hydrogen gas formed stick to the surface of the metal. (ii) to manufacture silicones, which are used for making waterproof clothes, greases and polishes. False… 3. Magnesium reacts with cold water. Mark ‘T’ if the statement is true and ‘F’ if it is false. B CuSO4 solution has a blue colour while ZnSO4 solution is colourless. copper is lower in the electrochemical series than zinc. Thus, it will replace iron.Zn + FeSO4 —> ZnSO4 + Fe. (ii) Iron (False) Question-5 Metallic sulphides of sulphur are used in the preparation of Ayurvedic medicines. Since the copper (II) ion has substantially greater reduction potential (+0.15 V) than zinc ion (-0.76 V), it is readily reduced by zinc metal. Which metals will react with cold water ? German silver has (copper/silver) as major constituent. 2K(s) + 2H2O(l) → 2KOH(aq) + H2(g) + heat energy. (vi) Mercury It is possible that the concentration of copper sulphate was lower and therefore less zinc reacted, releasing less energy than expected. [ ] Answer: (a) False (b) True (c) False (d) False… Potassium after combustion will form (acidic oxide/basic oxide). (d) Jewellery 3 mL CuSO4 + 3 mL Na2S When the number of mL of CuSO4 exceeded the number of mL of Na2S, what happened to the supernatant upon the addition of the test solution and what does that indicate? Record your observations in Table 4.1. Thus, it will not replace iron from iron sulphate. b) Immersion rods for heating liquids are made up of metallic substances because metals are good conductors of heat and electricity. Ans: .Bells are made of metals and not from wood because metals are sonorous but wood is not. ( ) Answer: (a) Generally, non-metals react with acids. It was found that blue colour of the solution gets fader and fader with the passage of time. ( ) (iii)Generally, non-metals react with acids. The metals copper, silver gold and … We can’t use pure gold to make jewellery. Metals like K and Na react vigorously with cold water to form hydrogen gas. (C) Copper displaces zinc from zinc sulphate solution. Describe any three properties of metal with suitable example? Sodium and potassium are stored in kerosene. [DAV2008]. List different uses of metals that you come across in everyday life. A zinc electrode and a copper electrode are placed in a beaker containing an aqueous solution of zinc sulfate, ammonium citrate, and ammonium chloride. The magnesium displaces the lead from solution to form magnesium nitrate, so magnesium must be more reactive than lead. gold, silver. 5. Examples: gold, silver, platinum. Zinc is a slightly brittle metal at room temperature and has a blue-silvery appearance when oxidation is removed. (a) Generally, non-metals react with acids. Aluminium is used to make electrical wire. Copper is purified by electrolysis. Cu + H2SO4 (conc.) 7. The Activity Series can also be used to explain why Iron is coated with Zinc (a process known as Galvanization) and why the Thermite reaction occours. A copper spoon had fallen into a container containing dil.HCl. Physical Properties of Metals and Non-metals. Sodium and potassium are highly reactive metals. Graphite is used as an electrode in the dry cell. ... Copper displaces zinc from zinc sulphate solution. Required fields are marked *. False ii. Q3. (a) Generally, non-metals react with acids. Give an example. 8. zinc is more reactive than copper hence it displaces the copper in copper sulphate solution to become zinc sulphate and copper metal is formed This is indicated by a colour change from blue to colourless. 1 What is the difference between the physical state of metals and non-metals at room temperature? The discrepancy is likely to be a combination of heat loss and error in determining the concentration of copper sulphate. The blue color of the aqueous copper (II) sulfate solution is due to the presence of the hexaaquacopper (II) ion in water. (Iodine/bromine) has antiseptic properties. Ans: The property of metals by which they can be beaten into thin sheets is known as malleability, e.g. d) Sodium and Potassium are highly reactive metals which readily reacts with atmospheric Oxygen to catch fire hence Sodium and Potassium are stored in kerosene. (v) Copper (ii) In general metals react with water to form a metal oxide or hydroxide and hydrogen gas. So zinc is more reactive than iron and copper. (c) Copper displaces zinc from zinc sulphate solution. 1. (a) Generally, non-metals react with acids. Q2. (d) A metal that reacts with oxygen without burning. Coal can be drawn into wires. Oxygen is evolved at the anode which reacts with aluminium to form a uniform protective layer of aluminium oxide. What is an alloy? (i) Sodium reacts vigorously with water, giving off a lot of heat. What would happen to it in three days time ? Mark ‘T’ if the statement is true and ‘F’ if it is false. Distinguish between metals and non-metals on the basis of these properties. making surgical instruments d. making bodies of aircraftse. Give reason: Chemical reaction does not take place when copper is added to iron sulphate solution. Ans: Electric wire is made up of copper because copper is god conductors of electricity. In the following question, a statement of Assertion (i) followed by a statement of Reason (R) is given. Give reasons. True or False and correct the incorrect statements. What are noble metals? Metals aremalleable and ductile in nature whereas non-metals are neither malleable nor ductile; they are brittle. (b) Electric wire copper is lower in the electrochemical series than zinc. (e) A metal that bums in oxygen with a bright light.Answer: (a) Generally, non-metals react with acids. This kind of reaction is known as displacement reaction. According to Arrhenius,''the colour of an electrolytic solution is the characteristic of its ions present in that solution.'' Answer: (a) False (b) True (c) False (d) False. What is the advantage of galvanized iron over tin-plated iron? Metals are …….. conductors of heat and ………. It will change from blue to red. This causes a slight loss in its weight. Choose the correct option out of the following choices: Assertion: Copper sulphate can be stored in zinc vessel. Hence, copper cannot displace zinc from a compound of zinc. ( ) 3. Some properties are listed in the following Table. State whether a displacement reaction will occur if the following are mixed. Water purification: Chlorine 8. Since Zinc is more reactive than Copper, Zinc displaces Copper from Copper sulphate to form Zinc sulphate and Copper. An alloy is usually made by mixing together metals in their molten form. Ans: When aluminium reacts with oxygen or water, it forms aluminium oxide which gets deposited as a thin layer on aluminium and presents further oxidation. F. 2. 1. Filled in gas balloon: – Helium 10. In the periodic table, Aluminum is a metal of Group 13 and copper, iron and zinc are transition metals. (d) Coal can be drawn into wires. About 60 words corrosion of metals, benefits, the risk of deficiency and potential effects... 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