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. 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? Blue color spot on potato around both wires. Greenish blue spot on potato around one wire. Blue color spot on potato around one wire Greenish blue spot on potato around both wires None 2. Which of the following is a chemical effect of electric current? Formation of gas bubbles on the electrodes Deposition of metals on the electrodes All of the above Change of color of solution None 3. The chemical effect produced by an electric current depends on: the nature of electrode none of the above the tester the conducting solution None 4. Which of the following gas is formed at the electrode connected to the negative terminal of the battery? Hydrogen gas Nitrogen gas Carbon dioxide gas Oxygen gas None 5. 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. 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 Assertion is correct and Reason is incorrect Assertion is incorrect and Reason is correct None 6. Which of the following statement is correct while testing for conduction of electricity in lemon juice using an LED tester? The current flows in the circuit of the tester. All of the above The bulb glows which indicates lemon juice is a good conductor of electricity. The liquid (lemon juice) allows the electric current to pass through. Hence, the circuit of tester is complete. None 7. Which of the following is true during electroplating? The metal gets transferred from one electrode to another All of the above The metal gets deposited from positive terminal of a battery to negative terminal of the battery. Some amount of metal gets dissolved in the solution of the electrolyte. None 8. When electric current is passed through water, hydrogen is deposited over : positive pole no dissociation negative pole both the poles None 9. Which of the following gas is formed at the electrode, connected to the positive terminal of the battery? Hydrogen gas Nitrogen gas Oxygen gas Carbon dioxide gas None 10. If electrodes are immersed in water and a current was passed, bubbles of ___________ and __________ are produced. oxygen and hydrogen nitrogen and carbon dioxide oxygen and carbon dioxide hydrogen and carbon dioxide None 11. Chemical effect of electric current may cause : change in colour of the solution all of above formation of gas bubbles at the electrodes deposit of metal on the electrodes None 12. 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 cheaper than Iron Tin is lighter than Iron Tin is less reactive than Iron Tin is more reactive than Iron None 13. When electric current is passed through water, dissociation is indicated __________ by color change in the form of bubbles both a and b none of above None 14. 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 15. Which of the following is an example of electroplating? All of the above Coating of chromium on many objects such as bath taps, car parts, etc. Coating of zinc on tin to make cans Coating of gold or silver on less expensive metals None 16. LED is better than bulb to use in a tester as : it glows even when weak current passes through it. all of the above it emits more light. it is cheaper. None 17. 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 18. What will happen, When an electric current is passed through a conducting solution? increase in resistance heating of solution cooling of solution chemical reactions within the solution None 19. Which of the following is added to make the copper sulphate solution more conducting? Carbonic acid Sulphuric acid Nitric acid Hydrochloric acid None 20. 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: conducting properties of liquid cannot be compared in this manner liquid B is a better conductor than liquid A liquid A is a better conductor than liquid B both liquids are equally conducting 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.
