Can you ex¬plain the reason? Question 3. The disposal of the used conducting solution after electroplating is hazardous and can cause environmental pollution. Solution: Question 4. What is LED? These questions will test your cognizance, understanding, evaluating and mathematical skills. LEDs emitting white light can be used instead of bulbs. (b) Alcohol Record your observations in Table 14.1. Question 1. Answer: Class 8 Science Chapter 13 Sound. Pour about two teaspoonfuls of distilled water in each of them. A metal is released in the electrolysis of a salt. Answer: Chromium has a good shine, it resists scratches and is corrosion resistant. CBSE Science Class 8 Chapter Wise Solved Q&A . Pour one teaspoon of lemon juice or vinegar in one cap. Place a small compass needle inside it. Add a few drops of dilute sulphuric acid to copper sulphate solution to make it more conducting. Give some uses of LED. The iodide ions (I- ) react with starch to turn blue black. All Living Science 2019 Solutions for class Class 8 Science are prepared by experts and are 100% accurate. (d) sides of the container Question 8. But when salt is dissolved in pure water, it conducts electricity. Sound can travel through. 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Synthetic Fibres and Plastics. Question 1. The rainwater showed deflection with the tester because it is not as pure as distilled water. First and second cap with acid and base respectively, conducts electricity whereas third cap having sugar dissolved in distilled water do not conduct electricity. Now remove the electrodes from the solution and look at them carefully. How would you classify lemon juice or vinegar—a good conductor or a poor conductor? (i) The wires in the circuit may be loosely connected. Tin is less reactive than iron. Most liquids that conduct electricity are solutions of …………, ………. Pour a cupful of water in a glass/ plastic bowl. needle the moment you dip the free ends of the tester in lemon juice? [NCERT] Again test. Question 11. Answer: Now dissolve a pinch of common salt in distilled water. If the magnetic compass shows deflection glows, it is a conductor, but if it does not deflect, it is an insulator. You can understand how light travels and how you can split and converge white light. Bring your tester over this cap and let the ends of the tester dip into lemon juice or vinegar as shown in Fig. What precautions should be observed when doing electroplating ? (a) Sea water Choose the correct answer. In liquids, the movement of charged particles (ions) carry current from anode to cathode terminals. The passage of an electric current through a solution causes ……………….. effects. (b) chemical Good/Poor Conducting Liquids. We have provided Chemical Effects of Electric Current Class 8 Science MCQs Questions with Answers to help students understand the concept very well. (a) conduction Answer: (a) conductor (d) electro refining (b), Question 3. [NCERT] If you are a student of class 8 who is using NCERT Textbook to study Science, then you must come across chapter 14 Chemical Effects of Electric Current . A cell is an example of conversion of If the tester is put in distilled water, the bulb of the tester does not glow. Hydrogen and Oxygen. There are specific disposal guidelines for environmental protection. Answer: may be the current is so weak that it does not heat the filament of the bulb allowing it to glow. What are insulators ? (d) chemical energy into magnetic energy 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. Answer: Question 9. Class 8 Science Chapter 14 Chemical Effects of Electric Current Question 1. What is the basic principle of electric pen ? Question 7. Insulators : distilled water, milk. Solution: If the ends of the wire of tester are touched for a long time, the cells will be finished very soon. What do you find? How can the magnetic effect be used as a tester ? Question 7. Answer: 14.1. Question 12. Question 10. Use the tester to test whether distilled water conducts electricity or not. This solution contains questions, answers, images, explanations of the complete chapter 14 titled Chemical Effects of Electric Current From of Science taught in class 8. Answer: Question 5. Chapter 1 Crop Production and Management Class 8 Extra Questions Chapter 2 Microorganisms: Friend and Foe Class 8 Extra Questions How should LED be connected ? Compass needle shows deflection due to magnetic effect of electric current. (b) pole (b) insulator Activity 2 (NCERT Textbook, Page 773) Or, your cells are used up? Add a few drops of lemon juice or dilute hydrochloric acid to distilled water in one cap. Answer: Materials which allow electric current to flow through them are called conductors. The NCERT Class 8 Science important questions come from this chapter. Answer: Answer: The free copper, being positively charged, gets drawn to the negative terminal of the battery and gets deposited on it. [NCERT] A tester is used to check the conduction of electricity through two liquids, labelled A and B. Check the below NCERT MCQ Questions for Class 9 Science Chapter 8 Motion with Answers Pdf free download. Recall the definition of a chemical change that you learnt in Class VII. Bridges and automobiles are prevented from rusting by plating them with zinc. Answer: What are conductors ? You would conclude that. Question 3. Classify the following liquids into conductors and insulators : lemon juice, , distilled water, tap water, milk. When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. After the electroplating of a spoon with silver, it was found that the anode has become thin. Answer: Materials which do not allow electric current to flow through them are called insulators. If they are, then replace the bulb with another bulb. MCQ Questions for Class 8 Science with Answers were prepared based on the latest exam pattern. 14.6. Now connect one free end of the wire to the terminal of a battery. Question 4. The Class 8 Science Chapter 14 Solutions are now made easy to understand all the concepts and topics related to the chapter precisely. (Instead of carbon rods, you may take two iron nails about 6 cm long.) Collect a few small plastic or rubber caps of discarded bottles and clean them. Connect the copper plates to the terminals of a battery and immerse them in copper sulphate solution (Fig. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. MCQ Questions for Class 9 Science with Answers were prepared based on the latest exam pattern. Which is the most common application of chemical effect of current ? Now rinse them with water and dry them. Answer: Question 11. Clean copper plates with sand paper. (c) liquids only. It cannot be said for sure that liquid does not conduct electricity because : Question 2. Chemical Effects of Electric Current Class 8 Extra Questions Science Chapter 14 Chemical Effects of Electric Current Class 8 Extra Questions Very Short Answer Questions Question 1. (c), Question 2. He finds that the compass needle deflects more in the case of seawater. Here is the list of Extra Questions for Class 8 Science with Answers based on latest NCERT syllabus prescribed by CBSE. (a), Question 4. Vedantu is a platform that provides free NCERT Solution and other study materials for students. (b), Question 6. Question 2. Attach the free ends of the wires to a LED. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Take care that the ends are not more than 1 cm apart but at the same time do not touch each other. It is concluded that when electric current is passed through the copper sulphate solution, copper sulphate dissociates into copper and sulphate. 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. What is electrolysis ? Wait for 3-4 minutes. Which out of the following does not conduct electricity ? Answer: Is it possible that the connections are loose? Activity 5 (NCERT Textbook, Page 176) Electroplating. But when salt is dissolved in distilled water and again tested, the bulb glows which shows that water containing salts conduct electricity. Name three liquids, which when tested in the manner shown in figure, may cause the magnetic needle to deflect. Do you find a coating over it? Answer: (c) Dilute sulphuric acid Compact Fluorescent Lamps. During electroplating, the silver metal from the anode is deposited on the cathode. Answer: The deflection in magnetic needle shows that the circuit is complete and the solution conducts electricity, i.e., it is a good conductor. The NCERT Class 8 Science Chapter 14 Question Answer guide further offers students some details on why they shouldn’t use their bare hands while performing different tests. This completes the circuit of the tester and the bulb should glow. Materials which allow electric current to flow through them are called conductors. Answer: Question 12. In each case observe whether the magnetic needle shows deflection or not. The salts separate out and deposit on the sides of the container. Decoration of articles by giving them a layer for e.g., silver plating on cutlery. Which of the following metal is not extracted by electrolysis? (ii) liquid B is a better conductor than liquid A. Wrap an electric wire a few times around the tray. Why ? Question 21. Leave the other end free. What colour is the coating? (c) cathode Method : Question 2. Therefore, we can be electrocuted in case we touch appliances with wet hands. Jaya sets up a circuit as given below. synthetic fibres and plastics class 8 notes. Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Name the gases formed when electric current is passed in water containing a few drops of acid ? NCERT Solutions Class 8 Science Chapter 18 Pollution of Air and Water – Here are all the NCERT solutions for Class 8 Science Chapter 18.This solution contains questions, answers, images, explanations of the complete chapter 18 titled Pollution of Air and Water From of Science taught in class 8. Take a filter paper soaked in potassium iodide solution to which a pinch of starch is added. (a) Most liquids that conduct electricity are solutions of ______ , ______ and ______ (c) half on the anode and half on the cathode The two free ends of wire are connected to the material to be tested. Explain why they do this. Topics and Sub Topics in Class 8 Science Chapter 14 Chemical Effects of Electric Current: Question 1. Question 3. Dip the ends of the wire in the given liquid. Also Read : – Class 6 Science NCERT Solution NCERT Class 6 Science Chapter 14 […] Activity 7 (NCERT Textbook, Page 177) Explain your answer. Explain the process of electroplating of copper. Answer: The water used in the water hoses is not pure water and is a good conductor of electricity. Water is a solution of salts and so it is a good conductor of electricity. Key Features of NCERT Solutions for Class 8 Science Chapter 13. [NCERT] Question 10. Answer: Answer: However, if the bulb does not glow, it means that the tester is not working. Here we Provide Class 6 Science Question Answer, Important Questions, MCQ for Various State Boards Students like CBSE, Haryana, uttar pradesh, mp and other state students. Answer: (a) gases only. 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 ? Answer: Class 9 Science Chapter 10 Extra Questions and Answers Gravitation. The process of depositing a layer of any desired metal on another material by means of electricity is called …………. (d) photodiode Deposits can be seen in containers uses for storing water. Reproduction Class 8 Science Chapter 9 as per NCERT Book used in CBSE and other Schools. Does pure water conduct electricity? Hydroxyl ions (OH )move towards the anode and oxygen is collected on it. Can we call the change taking place in the solution a chemical change? To her surprise, she found that the compass needle showed deflection. (a) magnetic energy into chemical energy No, it is highly dangerous to carry out the electrical repairs outdoors during the heavy downpour. Moreover, students will also learn about the dangerous effects of electricity and how it can harm us. A tester can be made by attaching one free end of the wire to a terminal of a battery and another wire from other terminal of the battery to a bulb. Connect the negative terminal of battery to the metal sheet. Vinegar, lemon juice and tap water. So, the deflection of the compass needle is more. 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. (b) solids only. Class 8 is one of the crucial stages of a student’s life. Can you explain the reason ? Class 8 Science Chapter 8 cell structure and functions is a very important topic as it is basic for all the biological studies. Answer: Answer: Firemen shuts off the main electrical supply for the area because water is a good conductor of electricity and the firemen can get electrocuted. Or, the bulb is fused? If not, what can we do to make it conducting ? Why should you not touch electrical appliances with wet hands ? Sound talks about the distinction between music and noise. CL provides CBSE Science prep material for class 8 students. Water is dissociated into its constituent gases, i.e., hydrogen and oxygen. The sea water contains more salts dissolved in it as compared to the tap water. The thick rod of impure copper plate is to be attached to the positive terminal of the battery because when electric current is passed through the copper sulphate solution, it gets dissociated into copper and sulphate. In containers, water evaporates slowly. Prepare a list of objects around you that are electroplated. Yes, the solution does conduct electricity. Browse further to download free CBSE Class 8 Science Worksheets PDF. The compass needle will show deflection with tap water, lemon juice and sodium chloride solution. So she collected some rainwater in a clean glass tumbler and tested it using a tester. The possible reasons for this are : Question 4. 14.5. may cause the magnetic needle to deflect. Answer: (d) semi-insulator We have provided Sound Class 8 Science MCQs Questions with Answers to help students understand the concept very well. Question 15. To her surprise she found that the compass needle showed deflection. Question 9. Question 8. Free PDF download of NCERT Solutions for Class 8 Science (Chemistry) Chapter 18 - Pollution of Air and Water solved by Expert Teachers as per NCERT (CBSE) Book guidelines. Changes of colour of solutions may occur depending on what solution and electrodes are used. All questions and answers from the Living Science 2019 Book of Class 8 Science Chapter 14 are provided here for you for free. Answer: Answer: Electric charge on ions is used for writing with an electric pen. Video Format solutions of all chapters are also available. The lesson covers the complete explanation of class 8 Chapter 9 Reproduction. This shows that distilled water does not conduct electricity. LEDs require very little energy and glow even if a small current is passing through the circuit. of distilled water in a clean and dry beaker. What is electroplating? (b), Question 8. Chromium is used for electroplating because it has a shiny appearance, does not corrode and is scratch resistant. What is the objective of electroplating ? Take the tray from inside a discarded matchbox. Materials which do not allow electric current to flow through them are called insulators. Answer: Students of class 8 will be writing national level exams … Answer: All Pollution of Air and Water Exercise Questions with Solutions to help you to revise complete Syllabus and Score More marks. Electrolysis is the breaking up of a compound from its solution on passing electric current through the electrolyte. (Remember to wash and wipe the ends of tester after testing each liquid). Answer: Is air an insulator or conductor of electricity ? A child staying in a coastal region test the drinking water and also the seawater with his tester. Question 3. MCQ Questions for Class 8 Science with Answers were prepared based on the latest exam pattern. This process is known as electroplating. Dissolve two teaspoonfuls of copper sulphate in it. (d) Potassium Question 13. It gets deposited on the Answer: So, the compass needle showed deflection. Explain. Make sure that the metal caps of the carbon rods are outside the water. Living Science 2019, 2020 Solutions for Class 8 Science Chapter 14 - Some Natural Phenomena Living Science 2019, 2020 Solutions for Class 8 Science Chapter 15 - Chemical Effects of Electric Current Living Science 2019, 2020 Solutions for Class 8 Science Chapter 16 - Reflection of Light ( ) (b) … The free copper gets drawn to the plate connected to the negative terminal of the battery and gets deposited on that plate. On the other hand the loss of copper from the solution is regained from the impure copper rod which is attached to the positive terminal of the battery. Answer: What results do you obtain? Question 2. What are insulators or poor conductors? Answer: NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations. NCERT Solutions for Class 8 Science Chapter 8 Cell-Structure and Functions English and Hindi Medium (Adhyay 8: Koshika – Sanrachana evam Prakarya) to Study online or View in Video Format or download free in PDF file free for session 2020-2021. Question 5. Why are LEDs more useful for testing the flow of electric current ? Question 6. (d) electroplating. Answer: (a) anode Question 17. Activity 1 (NCERT Textbook, Page 173) In Class 8 Science Chapter 3, the descriptions of man-made fires and their uses are given. Question 18. Question 1. Which electrode should be attached to the positive terminal of the battery and why? 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