Ncert – class 8- science – Chapter 11: Chemical Effects of Electric Current 1 Welcome to your Ncert - class 8- science - Chapter 11: Chemical Effects of Electric Current 1 1. Chemical effect of electric current may cause : deposit of metal on the electrodes formation of gas bubbles at the electrodes all of above change in colour of the solution None 2. In the experiment to test for conduction of electricity through potato, which of the following observations indicate that a potato is a conductor of electricity? Greenish blue spot on potato around one wire. Greenish blue spot on potato around both wires Blue color spot on potato around both wires. Blue color spot on potato around one wire None 3. Why do jewellery makers electroplate gold or silver on metals? To protect it from corrosion. To prevent spoilage of jewellery. To reduce cost. To make it shine. None 4. If electrodes are immersed in water and a current was passed, bubbles of ___________ and __________ are produced. nitrogen and carbon dioxide hydrogen and carbon dioxide oxygen and hydrogen oxygen and carbon dioxide None 5. Which of the following is true during electroplating? All of the above The metal gets transferred from one electrode to another Some amount of metal gets dissolved in the solution of the electrolyte. The metal gets deposited from positive terminal of a battery to negative terminal of the battery. None 6. Which of the following gas is formed at the electrode connected to the negative terminal of the battery? Hydrogen gas Oxygen gas Nitrogen gas Carbon dioxide gas None 7. Tin cans are the tin electroplated on iron. These Tin cans are used to preserve food items. Why not iron cans used without Tin coating? Tin is more reactive than Iron Tin is cheaper than Iron Tin is less reactive than Iron Tin is lighter than Iron None 8. The chemical effect produced by an electric current depends on: the tester the nature of electrode the conducting solution none of the above None 9. Which of the following is an example of electroplating? Coating of zinc on tin to make cans All of the above Coating of gold or silver on less expensive metals Coating of chromium on many objects such as bath taps, car parts, etc. None 10. When electric current is passed through water, hydrogen is deposited over : no dissociation both the poles positive pole negative pole None 11. Which of the following is a chemical effect of electric current? All of the above Formation of gas bubbles on the electrodes Change of color of solution Deposition of metals on the electrodes None 12. When electric current is passed through water, dissociation is indicated __________ in the form of bubbles none of above by color change both a and b None 13. Which of the following statement is correct while testing for conduction of electricity in lemon juice using an LED tester? All of the above The bulb glows which indicates lemon juice is a good conductor of electricity. The current flows in the circuit of the tester. The liquid (lemon juice) allows the electric current to pass through. Hence, the circuit of tester is complete. None 14. Which of the following is added to make the copper sulphate solution more conducting? Hydrochloric acid Nitric acid Sulphuric acid Carbonic acid None 15. Which of the following gas is formed at the electrode, connected to the positive terminal of the battery? Nitrogen gas Oxygen gas Carbon dioxide gas Hydrogen gas None 16. What will happen, When an electric current is passed through a conducting solution? chemical reactions within the solution heating of solution increase in resistance cooling of solution None 17. LED is better than bulb to use in a tester as : it is cheaper. all of the above it emits more light. it glows even when weak current passes through it. None 18. A tester is used to check the conduction of electricity through two liquids, labeled 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: liquid A is a better conductor than liquid B both liquids are equally conducting liquid B is a better conductor than liquid A conducting properties of liquid cannot be compared in this manner None 19. Assertion:Chromium plating is done on many objects like car parts, wheel rims and bath taps.Reason:The chromed layer can be decorative, provide corrosion resistance, ease cleaning procedures, or increase surface hardness. Assertion is correct and Reason is incorrect Assertion is incorrect and Reason is correct Both Assertion and Reason is correct and Reason is the correct explanation of Assertion Both Assertion and Reason is correct but Reason is not the correct explanation of Assertion None 20. In the experiment to test for conduction of electricity through a potato, the greenish blue color spot on the potato is useful in identifying : the positive terminal both A and B neither A nor B the negative terminal None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
