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 a potato, the greenish blue color spot on the potato is useful in identifying : the negative terminal the positive terminal both A and B neither A nor B None 2. Which of the following is true during electroplating? Some amount of metal gets dissolved in the solution of the electrolyte. All of the above The metal gets transferred from one electrode to another The metal gets deposited from positive terminal of a battery to negative terminal of the battery. None 3. 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 4. Chemical effect of electric current may cause : formation of gas bubbles at the electrodes change in colour of the solution all of above deposit of metal on the electrodes None 5. If electrodes are immersed in water and a current was passed, bubbles of ___________ and __________ are produced. hydrogen and carbon dioxide oxygen and carbon dioxide nitrogen and carbon dioxide oxygen and hydrogen 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. When electric current is passed through water, dissociation is indicated __________ both a and b in the form of bubbles none of above by color change None 8. Which of the following gas is formed at the electrode, connected to the positive terminal of the battery? Nitrogen gas Carbon dioxide gas Hydrogen gas Oxygen gas None 9. When electric current is passed through water, hydrogen is deposited over : positive pole both the poles negative pole no dissociation None 10. 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 one wire Greenish blue spot on potato around one wire. Greenish blue spot on potato around both wires Blue color spot on potato around both wires. None 11. The chemical effect produced by an electric current depends on: the conducting solution the nature of electrode none of the above the tester None 12. Which of the following is a chemical effect of electric current? Change of color of solution Deposition of metals on the electrodes All of the above Formation of gas bubbles on the electrodes None 13. What will happen, When an electric current is passed through a conducting solution? chemical reactions within the solution increase in resistance cooling of solution heating of solution None 14. Why do jewellery makers electroplate gold or silver on metals? To make it shine. To reduce cost. To prevent spoilage of jewellery. To protect it from corrosion. None 15. 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 less reactive than Iron Tin is lighter than Iron Tin is cheaper than Iron None 16. Which of the following statement is correct while testing for conduction of electricity in lemon juice using an LED tester? 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. All of the above None 17. Which of the following is added to make the copper sulphate solution more conducting? Hydrochloric acid Carbonic acid Sulphuric acid Nitric acid 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 B is a better conductor than liquid A both liquids are equally conducting liquid A is a better conductor than liquid B conducting properties of liquid cannot be compared in this manner None 19. LED is better than bulb to use in a tester as : it emits more light. it is cheaper. it glows even when weak current passes through it. all of the above None 20. Which of the following gas is formed at the electrode connected to the negative terminal of the battery? Hydrogen gas Carbon dioxide gas Nitrogen gas Oxygen gas 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.
