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. When electric current is passed through water, dissociation is indicated __________ in the form of bubbles both a and b none of above by color change None 2. 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 both liquids are equally conducting liquid A is a better conductor than liquid B liquid B is a better conductor than liquid A None 3. Which of the following is added to make the copper sulphate solution more conducting? Nitric acid Sulphuric acid Carbonic acid Hydrochloric acid None 4. Which of the following gas is formed at the electrode, connected to the positive terminal of the battery? Nitrogen gas Hydrogen gas Oxygen gas Carbon dioxide gas None 5. If electrodes are immersed in water and a current was passed, bubbles of ___________ and __________ are produced. oxygen and hydrogen hydrogen and carbon dioxide oxygen and carbon dioxide nitrogen and carbon dioxide None 6. Which of the following is an example of electroplating? Coating of gold or silver on less expensive metals Coating of zinc on tin to make cans Coating of chromium on many objects such as bath taps, car parts, etc. All of the above None 7. The chemical effect produced by an electric current depends on: the conducting solution none of the above the tester the nature of electrode None 8. When electric current is passed through water, hydrogen is deposited over : no dissociation both the poles negative pole positive pole None 9. Which of the following is a chemical effect of electric current? All of the above Change of color of solution Formation of gas bubbles on the electrodes Deposition of metals on the electrodes None 10. Which of the following statement is correct while testing for conduction of electricity in lemon juice using an LED tester? The liquid (lemon juice) allows the electric current to pass through. Hence, the circuit of tester is complete. 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. None 11. 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 lighter than Iron Tin is cheaper than Iron Tin is less reactive than Iron Tin is more reactive than Iron None 12. 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. Blue color spot on potato around one wire Blue color spot on potato around both wires. Greenish blue spot on potato around both wires None 13. What will happen, When an electric current is passed through a conducting solution? cooling of solution heating of solution increase in resistance chemical reactions within the solution None 14. LED is better than bulb to use in a tester as : it is cheaper. all of the above it glows even when weak current passes through it. it emits more light. None 15. 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 but Reason is not the correct explanation of Assertion Both Assertion and Reason is correct and Reason is the correct explanation of Assertion None 16. Which of the following is true during electroplating? All of the above The metal gets deposited from positive terminal of a battery to negative terminal of the battery. The metal gets transferred from one electrode to another Some amount of metal gets dissolved in the solution of the electrolyte. None 17. Which of the following gas is formed at the electrode connected to the negative terminal of the battery? Nitrogen gas Hydrogen gas Oxygen gas Carbon dioxide gas None 18. Why do jewellery makers electroplate gold or silver on metals? To prevent spoilage of jewellery. To protect it from corrosion. To reduce cost. To make it shine. None 19. Chemical effect of electric current may cause : formation of gas bubbles at the electrodes all of above deposit of metal on the electrodes change in colour of the solution 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 : neither A nor B both A and B the negative terminal the positive 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.
