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. Why do jewellery makers electroplate gold or silver on metals? To prevent spoilage of jewellery. To protect it from corrosion. To make it shine. To reduce cost. None 2. Which of the following is an example of electroplating? 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 All of the above None 3. If electrodes are immersed in water and a current was passed, bubbles of ___________ and __________ are produced. nitrogen and carbon dioxide oxygen and carbon dioxide oxygen and hydrogen hydrogen and carbon dioxide None 4. The chemical effect produced by an electric current depends on: none of the above the nature of electrode the conducting solution the tester None 5. Which of the following is added to make the copper sulphate solution more conducting? Hydrochloric acid Carbonic acid Nitric acid Sulphuric acid None 6. 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 both wires Blue color spot on potato around both wires. Greenish blue spot on potato around one wire. None 7. 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 8. 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 more reactive than Iron Tin is less reactive than Iron Tin is lighter than Iron None 9. LED is better than bulb to use in a tester as : it is cheaper. it emits more light. it glows even when weak current passes through it. all of the above None 10. When electric current is passed through water, hydrogen is deposited over : negative pole both the poles no dissociation positive pole None 11. 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 B is a better conductor than liquid A conducting properties of liquid cannot be compared in this manner liquid A is a better conductor than liquid B None 12. When electric current is passed through water, dissociation is indicated __________ both a and b in the form of bubbles by color change none of above None 13. Chemical effect of electric current may cause : formation of gas bubbles at the electrodes deposit of metal on the electrodes all of above change in colour of the solution None 14. Which of the following is true during electroplating? 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 The metal gets deposited from positive terminal of a battery to negative terminal of the battery. None 15. 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. The current flows in the circuit of the tester. All of the above None 16. Which of the following is a chemical effect of electric current? Change of color of solution Deposition of metals on the electrodes Formation of gas bubbles on the electrodes All of the above None 17. What will happen, When an electric current is passed through a conducting solution? heating of solution increase in resistance cooling of solution chemical reactions within the solution None 18. 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 19. 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 the negative terminal both A and B neither A nor B None 20. Which of the following gas is formed at the electrode connected to the negative terminal of the battery? Oxygen gas Hydrogen gas Nitrogen gas Carbon dioxide 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.
