The writing appears on the paper. You can understand how light travels and how you can split and converge white light. Question 11. The compass needle should show deflection. Visit to Discussion Forum to ask your doubt and reply to your classmates. Question 1. You will also love the ad-free experience on Meritnation’s Living Science 2019 Solutions. Answer: The bulb does not glow in the set-up shown in figure. [NCERT] Answer: Question 11. Answer: Take two pieces of copper wire and iron wire. Give three applications of chemical effect of current. Answer: Objective Questions existing will help in scoring well in the board exams as they are highly scoring and give you an extra edge to … (c) negative Synthetic Fibres and Plastics. Answer: Chapter 1 Crop Production and Management Class 8 Extra Questions Chapter 2 Microorganisms: Friend and Foe Class 8 Extra Questions Chromium is used for electroplating because it has a shiny appearance, does not corrode and is scratch resistant. Class 8 NCERT exercise wise questions and answers will help students frame a perfect solution in the Maths Exam. Bring your tester over this cap and let the ends of the tester dip into lemon juice or vinegar as shown in Fig. The free copper gets deposited on the plate acting as cathode. The two free ends of wire are connected to the material to be tested. Decoration of articles by giving them a layer for e.g., silver plating on cutlery. On passing electric current through the conducting solution of lemon juice and water, chemical reaction takes place. Which is the most common application of chemical effect of current ? You can refer to NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current to revise the concepts in the syllabus … Maths Students who are looking for better solutions, they can download Class 8 Maths NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations. After removing the electrodes from the solution, we find that copper metal gets deposited on the plate at the negative of the battery. Sorry!, This page is not available for now to bookmark. During electroplating, the silver metal from the anode is deposited on the cathode. Why we cannot make the whole article with chromium ? Answer: If the current in the circuit is small, how can we test its presence ? So she collected some rainwater in a clean glass tumbler aifd tested it using a tester. Choose the correct answer. Answer: Now test if the tester is working or not. of distilled water in a clean and dry beaker. Notes & Worksheet. Conducting properties of liquid cannot be compared in this manner. Oxygen bubbles are formed on the electrode connected to the positive terminal of the battery and hydrogen bubbles are formed on the other electrode. Materials which do not allow electric current to flow through them are called insulators. Chapter Wise CBSE Science Class 8 … The sea water contains more salts dissolved in it as compared to the tap water. (d) Potassium You can now go through the concise explanations offered in these NCERT Solutions for Class 8 Science to get the utmost clarity on different concepts under the chapter Chemical Effects of Electric Current. What are good conductors? In containers, water evaporates slowly. But the bulb does not glow. Question 6. This happens because the when current is passed, the K+ ions are attracted to the metal sheet. We can test the presence of the small current by using a LED instead of the bulb. 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. What is the difference between current flowing through metals and current flowing through liquids ? . We have provided Sound Class 8 Science MCQs Questions with Answers to help students understand the concept very well. Take out the ends of the tester from the lemon juice, dip them in water and then wipe them dry. (b) Iron Answer: Hydrogen and Oxygen. Pour one teaspoon of lemon juice or vinegar in one cap. Why? Answer: Electroplating is the process of depositing a thin film of one metal over another metal by passing electric current through an electrolyte. (d) Vinegar He finds that the compass needle deflects more in the case of seawater. Do you find a deflection in the compass Answer: 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. Yes, the solution does conduct electricity. (b) insulator Which one of the following is a weak electrolyte ? (d) Nitric acid Now in the second cap containing distilled water, add a few drops of a base such as caustic soda or potassium iodide. [NCERT] What is LED? (iv) conducting properties of liquid cannot be compared in this manner. 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. Explain why these deposits occur. Define the following terms. (b) Alcohol Take 250 ml. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. Dinesh can study the chemical effect of current at home very easily. (b), Question 6. The Class 8 Science Chapter 14 Solutions are now made easy to understand all the concepts and topics related to the chapter precisely. Given here is the complete explanation of the lesson, along with all the exercises, Question and Answers given at the back of the lesson. Answer: If not, what can we do to make it conducting ? Write its one use. Now rinse them with water and dry them. Pour about two teaspoonfuls of distilled water in each of them. NCERT Solutions for Class 8 Science Chapter 14 – 1 Mark Questions and Answers. (b), Question 3. In case of a fire, before the firemen uses the water hoses, they shut off the main electrical supply for the area. What can be the possible reasons for this ? Mark ‘T’ if the statement is true and ‘F’ if it is false. Answer: Question 3. The Sound Class 8 NCERT solutions provide questions and answers from the NCERT books in a very detailed way. Graphite. Electrolysis is the breaking up of a compound from its solution on passing electric current through the electrolyte. What results do you obtain? Answer: 14.5. may cause the magnetic needle to deflect. What do you conclude this time? Thus water which is free of salts are poor conductors while water with salts is a good conductor of electricity. Question 2. Question 7. Question 10. Why the iron cans are electroplated with tin ? (b) The passage of an electric current through a solution causes _______ effects. As pure water is free of salts and thus it is an insulator so to make pure water conducting, we can add some salts or acid to it. What colour is the coating? What are insulators or poor conductors? Join the free ends of the tester together fora moment. Insulators : distilled water, milk. Solution: Collect a few small plastic or rubber caps of discarded bottles and clean them. How are bridges and automobiles prevented from rusting ? Add a little sugar to the distilled water in the third cap and dissolve it. Name one non-metal which a good conductor of electricity. In Class 8 Science Chapter 3, the descriptions of man-made fires and their uses are given. (b), Question 8. Answer: Dip the ends of the wire in the given liquid. (iii) The cells may be used up. Name the gases formed when electric current is passed in water containing a few drops of acid ? Question 6. Paheli had heard that rainwater is as good as distilled water. Chapter 3: Synthetic Fibres and Plastics. Place a small compass needle inside it. Answer: The bulb does not glow in the setup shown in Fig. Can you think of the possible reasons? No, pure water doesn’t conduct electricity. synthetic fibres and plastics class 8 notes. Answer: Vinegar, lemon juice and tap water. Make sure that the metal caps of the carbon rods are outside the water. Does pure water conduct electricity? 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. Answer: Check that all the connections are tight. Question 21. The process that you saw in Activity 14.7 is used for purification of copper. Why is chromium used for electroplating ? Copper from impure rod is sought to be transferred to the thin copper plate. (a) Most liquids that conduct electricity are solutions of ______ , ______ and ______ Why are LEDs more useful for testing the flow of electric current ? This process is known as electroplating. Explain. Answer: What precautions should be observed when doing electroplating ? Iron is a strong metal used for making bridges. Answer: Which electrode should be attached to the positive terminal of the battery and why? A child staying in a coastal region test the drinking water and also the seawater with his tester. Question 6. Question 4. Pour a cupful of water in a glass/ plastic bowl. Answer: Allow the current to pass for about 15 minutes. Give the construction of LED. Attach the free ends of the wires to a LED. Add a teaspoonful of salt or a few drops of lemon juice to water to make it more conducting. Use the tester to test whether distilled water conducts electricity or not. The water used in the water hoses is not pure water and is a good conductor of electricity. Add a few drops of lemon juice or dilute hydrochloric acid to distilled water in one cap. All Pollution of Air and Water Exercise Questions with Solutions to help you to revise complete Syllabus and Score More marks. Answer: Distilled water does not have any salts dissolved in it, but rain water may have some impurities in it. Use plating artificial jewellery with gold. Electric charge on ions is used for writing with an electric pen. If the tester is working, it can be used to test the materials, i.e., whether it is a conductor or non-conductor of electricity. Question 8. In Chapter 8 of Grade 8 Science, we have to study about few synthetic fibres like Nylon, Rayon or Artificial Silk, Polyester and Acrylic.We should know about the properties of these synthetic fibres. 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 . Wrap copper wires around the metal caps of the carbon rods and join them to a battery (Fig. (c) semi-conductor The electrode, connected to the positive terminal of a battery, is called Wrap an electric wire a few times around the tray. Light: A chapter in the Science book for Class 8 deals with the concepts of light. Can you explain the reason? (a) Generally, non-metals react with acids. (a) conductor Check the below NCERT MCQ Questions for Class 9 Science Chapter 8 Motion with Answers Pdf free download. [NCERT] Is air an insulator or conductor of electricity ? Activity 1 (NCERT Textbook, Page 173) Activity 4 (NCERT Textbook, Page 175) Prepare a list of objects around you that are electroplated. Instead the iron can be galvanised or painted. (a) conduction Distilled water is a Answer: So, the compass needle showed deflection. 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