Read and download free pdf of CBSE Class 8 Science Chemical Effects of Electric Current Assignment Set C. Get printable school Assignments for Class 8 Science. Standard 8 students should practise questions and answers given here for Chapter 14 Chemical Effects Of Electric Current Science in Grade 8 which will help them to strengthen their understanding of all important topics. Students should also download free pdf of Printable Worksheets for Class 8 Science prepared as per the latest books and syllabus issued by NCERT, CBSE, KVS and do problems daily to score better marks in tests and examinations
Assignment for Class 8 Science Chapter 14 Chemical Effects Of Electric Current
Class 8 Science students should refer to the following printable assignment in Pdf for Chapter 14 Chemical Effects Of Electric Current in standard 8. This test paper with questions and answers for Grade 8 Science will be very useful for exams and help you to score good marks
Chapter 14 Chemical Effects Of Electric Current Class 8 Science Assignment
ChEMICAL EFFECTS OF ELECTRIC CURRENT
Question 1. Fill the blanks.
(a) Most liquids that conduct electricity are solutions of acids, bases and salts.
(b) The passage of an electric current through a solution causes chemical effects.
(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the negative terminal of the battery.
(d) The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating.
Question 2. When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?
Answer- Yes, because solution is conductor of electricity.
Question 3 Name three liquids, which when tested in the manner shown in Fig.14.9 may cause the magnetic needle to deflect.
Answer- Vinegar, Lemon juice and tap water.
Question 4. The bulb does not glow in the setup shown in fig. 14.10. List the possible reasons. Explain your answer.
Answer- The bulb may not glow because of the following reasons:
(i) Liquid in the beaker may be non-conducting.
(ii) The battery may be exhausted and does not have sufficient energy to generate electricity.
(iii) The bulb may be fuse.
(iv) Connections may be loose.
Question 5. A tester is used to check the conduction of electricity through two liquids. Labelled A and B. it is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. you would conclude that
(i) Liquid A is a better conductor than liquid B (✓)
(ii) Liquid B is a better conductor than liquid A
(iii) Both liquids are equally conducting
(iv) Conducting properties of liquid cannot be compared in this manner.
Question 6- Does pure water conduct electricity? If not, what can we do to make it conducting?
Answer- No. Pure water does not conduct electricity. This is because pure water do not have any free ion. Pure water can conduct electricity when a pinch of common salt is added to it, as salt solution is conducting in nature.
Question 7. In case of fire, before the firemen use the water hoses, they shut off the main electric supply for the area. Explain why they do this.
Answer- Water usually contains salts and conducts electricity. If the electrical supply is not cut off and firemen come in contact with wet electric switches, electric wires and other electrical appliances, he can get electric shock.
Question 8. A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?
Answer- Water we use for drinking purposes has very less amount of salts dissolved in it while sea water has very high concentration of salts in it. So, compass needle shows more deflection in case of sea water.
Question 9. Is it safe for the electrician to carry out electrical repairs outdoors during heavy rain pour? Explain.
Answer- No. It is not safe to repair electrical appliances outdoors during heavy downpour. This is because rain water contains small amounts of acids in it which makes it a conductor of electricity. So, the electrician may get electrical shocks while working outdoors during rain.
Question 10- Paheli had heard that rainwater is as good as distilled water. So, she collected some rainwater in a clean glass tumbler and tested it using a tester. To her surprise she found that the compass needle showed deflection. What could be the reason?
Answer- Rain water is said to be pure water. But many impurities and acidic gases get dissolved in the rain water while it falls to the earth through the atmosphere. Due to the presence of these impurities and small amounts of acids in it, the rainwater conducts electricity.
Question 11. Prepare a list of objects around you that are electroplated.
Answer- The objects which are electroplated are:
(i) Taps of water connection.
(ii) Parts of bicycle.
(iii) Body of cars, motor cycle and tractors.
(iv) Handles of the doors.
Question 12- The process that you saw in Activity 14.7 is used for purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?
Answer- The thick rod of impure copper should be attached to the positive terminal of battery. This is because the copper ions of the solution will get deposited on the thin rod and the loss of copper from the solution will be restored from the thick rod to the positive terminal of the battery. Thus, copper from the thick rod could be extracted out..
Click on link below to download CBSE Class 8 Science Chemical Effects of Electric Current Assignment Set C
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