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 : both A and B neither A nor B the negative terminal the positive terminal None 2. 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 3. Chemical effect of electric current may cause : change in colour of the solution all of above deposit of metal on the electrodes formation of gas bubbles at the electrodes None 4. 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 both wires Blue color spot on potato around one wire Greenish blue spot on potato around one wire. None 5. Which of the following is added to make the copper sulphate solution more conducting? Carbonic acid Nitric acid Sulphuric acid Hydrochloric acid None 6. Which of the following is true during electroplating? The metal gets deposited from positive terminal of a battery to negative terminal of the battery. All of the above Some amount of metal gets dissolved in the solution of the electrolyte. The metal gets transferred from one electrode to another None 7. What will happen, When an electric current is passed through a conducting solution? increase in resistance chemical reactions within the solution heating of solution cooling of solution None 8. 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 9. The chemical effect produced by an electric current depends on: the conducting solution the tester the nature of electrode none of the above None 10. Which of the following gas is formed at the electrode, connected to the positive terminal of the battery? Nitrogen gas Carbon dioxide gas Oxygen gas Hydrogen gas None 11. 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 liquid (lemon juice) allows the electric current to pass through. Hence, the circuit of tester is complete. All of the above The current flows in the circuit of the tester. None 12. If electrodes are immersed in water and a current was passed, bubbles of ___________ and __________ are produced. oxygen and hydrogen oxygen and carbon dioxide nitrogen and carbon dioxide hydrogen and carbon dioxide None 13. When electric current is passed through water, hydrogen is deposited over : negative pole no dissociation both the poles positive pole None 14. 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 incorrect and Reason is correct Assertion is correct and Reason is incorrect 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 15. 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: both liquids are equally conducting liquid A is a better conductor than liquid B conducting properties of liquid cannot be compared in this manner liquid B is a better conductor than liquid A None 16. 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 more reactive than Iron Tin is cheaper than Iron Tin is less reactive than Iron None 17. Which of the following gas is formed at the electrode connected to the negative terminal of the battery? Oxygen gas Nitrogen gas Carbon dioxide gas Hydrogen gas None 18. Which of the following is a chemical effect of electric current? Change of color of solution All of the above Formation of gas bubbles on the electrodes Deposition of metals on the electrodes None 19. LED is better than bulb to use in a tester as : all of the above it glows even when weak current passes through it. it is cheaper. it emits more light. None 20. Which of the following is an example of electroplating? Coating of zinc on tin to make cans Coating of gold or silver on less expensive metals All of the above Coating of chromium on many objects such as bath taps, car parts, etc. 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.
