Answer: Record your observations in Table 14.1. (c) half on the anode and half on the cathode Question 1. Answer: Place a small compass needle inside it. Is air an insulator or conductor of electricity ? However, if the bulb does not glow, it means that the tester is not working. (a) Sea water But when salt is dissolved in pure water, it conducts electricity. Question 5. List the possible reasons. Question 9. List the possible reasons. Electrical charge. If not, what can we do to make it conducting? Answer: (b) Oxalic acid Name the gases formed when electric current is passed in water containing a few drops of acid ? Make sure that the metal caps of the carbon rods are outside the water. Answer: If the tester is put in distilled water, the bulb of the tester does not glow. 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. 7. How can you make a tester for testing whether a given material is a conductor or an insulator ? Answer: The electrical resistivity of few materials is given below in ohm-meter. The writing appears on the paper. Thus food, stored in iron cans, is prevented from being spoilt due to iron by electroplating it by tin. Grade 8 Science - Electricity. The free copper gets drawn to the plate connected to the negative terminal of the battery and gets deposited on that plate. Explain. Answer: The major uses of electricity and their shares of total electricity use by the commercial sector in 2014 were 2. machine drives (motors)48.2% 3. process heating and boiler use14.4% 4. facility heating, ventilation, air conditioning, and cooling9.5% 5. electrochemical processes6.8% 6. process cooling and refrigeration7.3% 7. lighting6.5% 8. other miscellaneous processes and facility uses7.3% Protection of the surface of bases metals which corrode for e.g., iron is plated with chromium. First and second cap with acid and base respectively, conducts electricity whereas third cap having sugar dissolved in distilled water do not conduct electricity. A child staying in a coastal region test the drinking water and also the seawater with his tester. Do you find any difference in any one of them? In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Now test if the tester is working or not. Can you explain the reason ? Compact Fluorescent Lamps. So, the compass needle showed deflection. Answer: What could be the reasons ? These Class 8 trucks stand out, not only for their appealing exteriors but for the latest computer technology, keeping them steps ahead of other manufacturers’ trucks. Understanding the power of electricity we humans harness is necessary for the wise use and creation of this valuable resource. Solving the Chemical Effects of Electric Current Multiple Choice Questions of Class 8 Science Chapter 14 MCQ can be of extreme help as you will be aware of all the concepts. Calculate the electricity bill of the household for the month of June if the cost per unit of electric energy is Rs. 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