Answer: (d) sides of the container [NCT 2011] Vinegar, lemon juice and tap water. Question 3. Question 7. Now connect one free end of the wire to the terminal of a battery. Answer: In this activity the bulb glows which shows that lemon juice and vinegar both conducts electricity, hence they are good conductors of electricity. In general, all electroplating systems are made from three elements, the anode and cathode and the electrolyte … (a) anode First and second cap with acid and base respectively, conducts electricity whereas third cap having sugar dissolved in distilled water do not conduct electricity. EXAMPLE SPECIFICIATION: DONT USE CADMIUM ANY MORE, PLEASE. A cyanide-copper solution is still used for this purpose and also for the initial plating on zinc die castings. Answer: (a) a good conductor. Chromium has a good shine, it resists scratches and is corrosion resistant. Electroplating process - definition In electroplating, the article (metal) to be coated is taken as the cathode.The metal to be deposited over it would be the anode and … Now rinse them with water and dry them. Why should you not do the experiments on electricity by using electric supply from mains ? The passage of an electric current through a solution causes ……………….. effects. Gradually, a layer of copper builds up on the plate. 343 Views. So, the deflection of the compass needle is more. How are bridges and automobiles prevented from rusting ? Thus, lemon juice, vinegar, tap water, milk, curd and water, and soda are good conductors of electricity while vegetable oil, honey, kerosene oil, and distilled water are poor conductors of electricity or insulators. In this activity, if the bulb does not glow, it means that either the connections of the circuit are loose or the bulb is fused or cells are used up. (d) electroplating. NCERT Books. Answer: Answer: Question 5. What is electrolysis ? Top Question 1. LEDs require very little energy and glow even if a small current is passing through the circuit. Rack electroplating: Rack or wiring plating is a good option if you need to plate large groups of parts. Jaya sets up a circuit as given below. Learn the concepts of Class 8 Physics Chemical Effects of Electric Current with Videos and Stories. What could be the reasons ? (i) liquid A is a better conductor than liquid B. Answer: Give some applications of electroplating. In liquids, the movement of charged particles (ions) carry current from anode to cathode terminals. Explain why they do this. How would you classify lemon juice or vinegar—a good conductor or a poor conductor? This shows that distilled water does not conduct electricity. If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the ……….. terminal of the battery. CBSE 8 Science 01 Crop Production and Management 7 Topics | 8 Quizzes 1.1 Agricultural Practices and Cropping Pattern 1.01 Agricultural Practices and Cropping Pattern . So, the compass needle showed deflection. Question 5. What is LED? (a) conduction Air is an insulator of electricity. Electrode is a medium of conduction of electricity. Distilled water does not have any salts dissolved in it, but rain water may have some impurities in it. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. Answer: Question 10. Clean copper plates with sand paper. Answer: List the possible reasons. Answer: Electroplating Mention the components of the circuit of tester How will you identify the positive … What are electrodes? If not, what can we do to make it conducting? 14.5. may cause the magnetic needle to deflect. Activity 4 (NCERT Textbook, Page 175) Give three applications of chemical effect of current. If not, what can we do to make it conducting ? Use plating artificial jewellery with gold. Write its one use. Answer: Question 12. The writing appears on the paper. 2. Question 18. But when salt is dissolved in pure water, it conducts electricity. 14.1. Answer: Gradually, a layer of copper builds up on the plate. Answer: [NCERT] Answer: Now test if the tester is working or not. "a3-3" is probably some description of the chromating requirement but I'm not sure. ZYCI PLATING SPECIFICATIONS - GENERAL INFORMATION Page 8 Reference Only April 2018 CHEMICAL FILM / CHROMATE MIL-C-5541 Coatings for aluminum, zinc, silver, and cadmium. Electrolysis is the breaking up of a compound from its solution on passing electric current through the electrolyte. If the ends of the wire of tester are touched for a long time, what will happen ? Answer: How can he do it ? The number indicates the coating thickness in microns (µm). Liquid A is a better conductor of electricity because the bulb glows more in it. Protection of the surface of bases metals which corrode for e.g., iron is plated with chromium. Watch Now. Repeat the activity with other liquids such as tap water, vegetable oil, milk, honey. The compass needle should show deflection. Copper is (a) a good conductor (b) an insulator (c) both (a) and (b) (d) none of these. Uses of Electroplating and its application in the practical world are provided here. 1. From the other plate, an equal amount of copper gets dissolved in the solution. Electrode is a medium of conduction of electricity. The disposal of waste products produced during the proces of electroplating is a major problem. Electrolysis is a method that uses a DC to drive a non-spontaneous chemical reaction. Question 12. Chemical Effects of Electric Currents Class 8 Science Chapter 14 as per NCERT Book used in CBSE and other Schools. Question 4. Question 1. may be the current is so weak that it does not heat the filament of the bulb allowing it to glow. Answer: For example: All metals including metal wires, copper wires, aluminium foil, etc. The two free ends of wire are connected to the material to be tested. Therefore, it becomes thin. Zinc plating is identical to electro-galvanizing in principle because both are electro-deposition processes. Answer: Dec 20, 2020 - What is Electroplating and How is it Done? 3. Now repeat Activity 14.2 using this tester. Wait for 3-4 minutes. This may be done for a number of reasons. Take about two teaspoonfuls of distilled water in a clean and dry plastic or rubber cap of a bottle. Why we cannot make the whole article with chromium ? CIP specializes in the unique process of mechanical plating and galvanizing that provides excellent corrosion resistance. Depending on the coatings, or combinations of coatings, selected a variety of outcomes can be gained. NCERT Solutions for Class 8 Science Chapter 14 – 1 Mark Questions and Answers. Answer: Apparently "MF" means a ferrous substrate in lots of different Japanese specs; "Zn-Ni" means zinc-nickel plating, "8" probably means 8 micron plating thickness. Answer: What can be the possible reasons for this ? Call today! Does distilled water conduct electricity? Answer: Dinesh is wants to study the chemical effect of current at home. Observe the electrodes carefully. Materials for use in moderate or severe applications must be chromate conversion coated. Electroplating: It is the most common application of the chemical effect of electric current is electroplating. Can we do electroplating on it to protect is from corrosion ? Check that all the connections are tight. Give some uses of LED. Solution: The electrodepositing reaction takes place in an electrolytic solution… (c) negative Class … Name three liquids, which when tested in the manner shown in Fig. (b) chemical (You may obtain distilled water from your school science lab. But when salt is dissolved in distilled water and again tested, the bulb glows which shows that water containing salts conduct electricity. Pollutants from electroplating industries are very harmful. Question 3. In this article we will talk in … Distilled water is a Fill in the blanks. Insulators : distilled water, milk. Electroplating is a process that uses electric current to reduce dissolved metal ions by the use of electrolysis. A tester is used to check the conduction of electricity through two liquids, labelled A and B. Question 13. Question 15. If the tester is put in distilled water, the bulb of the tester does not glow. Explain the process of electroplating of copper. The waste conducting solution pollutes the environment. Do you find a coating over it? By volume of hydrogen gas is twice the volume of oxygen gas. Activity 7 (NCERT Textbook, Page 177) Iron is a strong metal used for making bridges. Electric charge on ions is used for writing with an electric pen. Explain why they do this. Question 7. Explain your answer. What are electrodes ? We should not do the experiments on electricity by using electric supply from the mains because there is large amount of current and the person using it can get electrocuted. This makes them look more attractive and also resist corrosion. So, the fire¬men shut off the electric supply before spraying water to save themselves and other people from electrocution. Write short note on. Math- Science Championship. Answer: He finds that the compass needle deflects more in the case of seawater. However, if the bulb does not glow, it means that the tester is not working. Add a few drops of dilute sulphuric acid to copper sulphate solution to make it more conducting. Question 6. Which out of the following does not conduct electricity ? Watch Now. Artificial jewellery is plated with silver or gold. Parts of bicycle, motorbike and sanitary fittings are chrome plated by this method. Note down the terminal of the battery with which this electrode is connected. Instead the iron can be galvanised or painted. Record your observations in Table 14.1. The iodide ions (I- ) react with starch to turn blue black. Answer: (b), Question 3. The free copper gets drawn to the plate connected to the negative terminal of the battery and gets deposited on that plate. Question 8. Question 6. Though more expensive, this option is optimal for more delicate parts that cannot undergo barrel plating. (a) Aluminium Activity 6 (NCERT Textbook, Page 176) Electrodes are the metal rods which are dipped in liquids, to which cells are attached are called electrodes. Explain how it can be used for writing. NCERT Solutions for Class 8 Science Chapter 14 – 1 Mark Questions and Answers. Join the free ends of two wires momentarily. Similar Classes. If the ends of the wire of tester are touched for a long time, the cells will be finished very soon. Answer: Nabamita Bhattacharjee. Answer: Some chemicals are very lethal for both human and animals. The seawater contains a huge amount of salts in comparison to drinking water, hence the seawater is a better conductor of electricity and it produces a stronger magnetic field in the wire and hence deflects the compass needle more. In what proportion the two products from electrolysis of water are obtained ? Wrap copper wires around the metal caps of the carbon rods and join them to a battery (Fig. Attach the free ends of the wires to a LED. Math- Science Championship. It is also called the substrate. Electroplating is the process in which a coating of one metal can be deposited on the surface of another metal by using current from a battery. The bulb does not glow in the setup shown in Fig. (b), Question 6. Question 2. Question 13. Solution: Commercial zinc-yellow plating has a standard minimum thickness of 0.00020 inches. It cannot be said for sure that liquid does not conduct electricity because : Question 2. Add a few drops of lemon juice or dilute hydrochloric acid to distilled water in one cap. Conclusion. Answer: The current is provided by an external power supply. CBSE Class 10; CBSE Class 12; JEE Main Papers; JEE Advanced Papers; NEET Papers; KCET Papers; Mock Tests. Now in the second cap containing distilled water, add a few drops of a base such as caustic soda or potassium iodide. No, pure water doesn’t conduct electricity. Can we call the change taking place in the solution a chemical change? (ii) The bulb may be fused. Electroplating is conducted in an electrolytic cell. (d) photodiode Name three liquids, which when tested in the manner shown in figure, may cause the magnetic needle to deflect. We cannot make the whole article from it because it is a very costly metal. (a) Copper The coating finds application in screws and other light fasteners, light switch plates and other small parts. Answer: A cell consists of two electrodes (conductors), usually made of metal, which are held apart from one another. The Guardian, April 29, 2015. (i) liquid A is a better conductor than liquid B. 8 and smaller may not accommodate this thickness. Question 12. Stainless steel revolutionised eating after centuries of a bad taste in the mouth by Mark Miodownik. Answer: (b) chemical effect of electricity. Answer: (c) semi-conductor Take a filter paper soaked in potassium iodide solution to which a pinch of starch is added. It is … What is electroplating? Answer: Your IP: 184.108.40.206 Solution: Answer: The longer lead (leg) from the LED should be connected to the positive terminal of the battery and the shorter lead to the negative terminal of the battery. In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. (d) Vinegar If they are, then replace the bulb with another bulb. Good/Poor Conducting Liquids. Why ? Oxygen bubbles are formed on the electrode connected to the positive terminal of the battery and hydrogen bubbles are formed on the other electrode. The zinc is applied as an expendable electrode in a cyanide, alkaline non-cyanide, or acid chloride salt solution. Video on Electroplating Class 8 Science Chapter 14 Chemical Effects Of Electric Current for CBSE Board explaining the process of electroplating with activity. Electroplating can be described as an application of electrolysis since electrolysis is the basic technique used for electroplating. We have seen many times wherein artificial jewellery is shining when it is new and after sometime it begins to lose its shine. 14.4). Please enable Cookies and reload the page. (ii) liquid B is a better conductor than liquid A. Again test. Define Electroplating and understand it using an activity. Hydroxyl ions (OH )move towards the anode and oxygen is collected on it. Why? Good conductors are those conductors that allow current to pass through them. Electrodes are the metal rods which are dipped in liquids, to which cells are attached are called electrodes. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Some Uses of Electroplating: Imitation jewelry is made by applying a layer of gold or silver. Answer: He finds that the compass needle deflects more in the case of seawater. In metals electric current is conducted by flow of electrons. What is the difference between current flowing through metals and current flowing through liquids ? Add a little sugar to the distilled water in the third cap and dissolve it. The free copper gets deposited on the plate acting as cathode. (iv) conducting properties of liquid cannot be compared in this manner. Topics and Sub Topics in Class 8 Science Chapter 14 Chemical Effects of Electric Current: Question 1. BNAT; Classes. What could be the reasons? Answer: Share. No, it is not advisable for electrician to carry out electrical repairs during heavy downpour because water is a good conductor of electricity and the person can get shock. What results do you obtain? Answer: 206k watch mins. Question 8. Hello Cintadi. Clean their metal caps with sand paper. Gold does not corrode. Fasteners of High tensile class 12.9 are generally supplied unplated with an oil quenched finish, where the vast majority of lower tensile fasteners are coated; this includes Metric class 8.8, USA grade 5 and lower grade/class. Answer: Is it possible that the connections are loose? Thus water which is free of salts are poor conductors while water with salts is a good conductor of electricity. Which of the following metal is not extracted by electrolysis? The free copper, being positively charged, gets drawn to the negative terminal of the battery and gets deposited on it. Question 14. Liquid B is a better conductor than liquid A. Answer: Question 20. and ………….. Class 8 Physics Chemical Effects of Electric Current: Electroplating: Electroplating. (i) The wires in the circuit may be loosely connected. Electroplating is a process that uses electric current to reduce dissolved metal ions by the use of … Does pure water conduct electricity ? Consider the following statements about electroplating: I. Electroplating is the coating of metal objects with a thin layer of a different metal. Electroplating is based on (a) heating effect of electricity (b) chemical effect of electricity (c) physical effect of electricity (d) magnetic effect of electricity . So she collected some rainwater in a clean glass tumbler and tested it using a tester. Changes of colour of solutions may occur depending on what solution and electrodes are used. 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