Lets not check out some of the important MCQ questions for Chemical Effects of Electric Current, Chapter 11 from Class 8 Science NCERT book.
Class 8 Science Chapter 11 MCQ Online Test Questions and Answers
Question 1. What conducts electricity in water?
a) Oxygen
b) Dissolved salts and minerals
c) Nitrogen
d) Carbon
Answer:
b) Dissolved salts and minerals
Question 2. What happens when electric current passes through a solution?
a) Generates heat only
b) Causes a chemical reaction
c) Produces magnetic effect only
d) Stops flow of current
Answer:
b) Causes a chemical reaction
Question 3. What is electroplating?
a) Depositing a layer of metal using electricity
b) Painting a metal surface
c) Cleaning metal using electricity
d) Testing electrical circuits
Answer:
a) Depositing a layer of metal using electricity
Question 4. What is the purpose of an LED in a tester?
a) To generate heat
b) To detect weak current
c) To conduct electricity
d) To reduce current flow
Answer:
b) To detect weak current
Question 5. What are electrodes?
a) Liquid solutions
b) Conducting rods or plates
c) Insulating wires
d) Glass components
Answer:
b) Conducting rods or plates
Question 6. What metal is commonly used for electroplating jewelry?
a) Copper
b) Chromium
c) Gold
d) Zinc
Answer:
c) Gold
Question 7. What can be used as an electrolyte for electroplating?
a) Sand
b) Distilled water
c) Copper sulfate solution
d) Hydrogen gas
Answer:
c) Copper sulfate solution
Question 8. What indicates good conduction in a liquid?
a) LED glows
b) Tester stops working
c) Wire heats up
d) Current stops flowing
Answer:
a) LED glows
Question 9. What is a poor conductor of electricity?
a) Metal
b) Distilled water
c) Copper wire
d) Salt water
Answer:
b) Distilled water
Question 10. What protects food cans from corrosion?
a) Electroplating with zinc
b) Coating with tin
c) Painting with oil
d) Electroplating with silver
Answer:
b) Coating with tin
Question 11. What is a chemical effect of electric current?
a) No visible reaction
b) Formation of bubbles
c) Heating of electrodes only
d) No current flow
Answer:
b) Formation of bubbles
Question 12. What forms on the positive electrode during electrolysis of water?
a) Hydrogen bubbles
b) Oxygen bubbles
c) Sulfate deposits
d) Acid particles
Answer:
b) Oxygen bubbles
Question 13. Which liquid is a good conductor of electricity?
a) Distilled water
b) Pure alcohol
c) Saltwater
d) Vegetable oil
Answer:
c) Saltwater
Question 14. What effect does adding salt to distilled water have?
a) Makes it non-conductive
b) Improves conduction
c) Stops electricity flow
d) Destroys electrodes
Answer:
b) Improves conduction
Question 15. What is deposited on the cathode during electroplating?
a) Gas bubbles
b) Metal ions
c) Acidic solution
d) Non-conducting material
Answer:
b) Metal ions
Question 16. Why should electrical repairs not be done with wet hands?
a) It is inefficient
b) Water increases conductivity
c) Hands may dry out
d) Current will stop flowing
Answer:
b) Water increases conductivity
Question 17. What protects iron objects from rusting?
a) Painting
b) Electroplating with zinc
c) Heating
d) Sandblasting
Answer:
b) Electroplating with zinc
Question 18. What is the role of sulfuric acid in electroplating?
a) Reduces conductivity
b) Prevents reaction
c) Increases conductivity
d) Creates bubbles
Answer:
c) Increases conductivity
Question 19. What metal is commonly electroplated on bicycle handlebars?
a) Chromium
b) Copper
c) Zinc
d) Tin
Answer:
a) Chromium
Question 20. What does the term “anode” refer to?
a) Positive electrode
b) Negative electrode
c) Neutral electrode
d) Insulating wire
Answer:
a) Positive electrode
Question 21. What is the most common use of electrolysis in industries?
a) Generating electricity
b) Electroplating and refining metals
c) Heating elements
d) Producing sound
Answer:
b) Electroplating and refining metals
Question 22. What is the role of a battery in a circuit with liquid conductors?
a) To produce heat
b) To supply current
c) To dissolve liquid
d) To reduce resistance
Answer:
b) To supply current
Question 23. Which material is often used for making electrodes?
a) Plastic
b) Wood
c) Graphite
d) Cotton
Answer:
c) Graphite
Question 24. What happens to the electrolyte during electroplating?
a) It evaporates
b) It breaks into ions
c) It becomes non-conductive
d) It solidifies
Answer:
b) It breaks into ions
Question 25. Why is copper electroplated on steel utensils?
a) To improve durability
b) To increase weight
c) To reduce heat conductivity
d) To change color
Answer:
a) To improve durability
Question 26. What causes greenish deposits on copper surfaces?
a) Corrosion due to moisture
b) High temperatures
c) Electroplating with silver
d) Rusting due to oxygen
Answer:
a) Corrosion due to moisture
Question 27. Which type of current is used in electroplating?
a) Direct current (DC)
b) Alternating current (AC)
c) Static current
d) Magnetic current
Answer:
a) Direct current (DC)
Question 28. Which gas is released at the cathode during electrolysis of water?
a) Hydrogen
b) Oxygen
c) Nitrogen
d) Carbon dioxide
Answer:
a) Hydrogen
Question 29. Why do electrical testers have insulated handles?
a) To ensure conductivity
b) To prevent electric shocks
c) To reduce resistance
d) To amplify current
Answer:
b) To prevent electric shocks
Question 30. What makes vinegar a conductor of electricity?
a) Presence of sugar
b) Acetic acid content
c) Presence of oil
d) Absence of ions
Answer:
b) Acetic acid content
Question 31. What is the main advantage of electroplating?
a) Enhances corrosion resistance
b) Increases thickness
c) Improves insulation
d) Reduces conductivity
Answer:
a) Enhances corrosion resistance
Question 32. What effect does distilled water have on an electrical tester?
a) It makes the tester glow brightly
b) It makes the tester stop glowing
c) It reduces resistance
d) It generates heat
Answer:
b) It makes the tester stop glowing
Question 33. What is the function of a salt bridge in an electrochemical cell?
a) To transfer heat
b) To complete the circuit
c) To stop ion flow
d) To create electricity
Answer:
b) To complete the circuit
Question 34 – Match the Following
| Column A | Column B |
|---|---|
| 1. Process of electroplating | A. Increases conduction |
| 2. Material used in electrodes | B. Salt bridge |
| 3. Role of sulfuric acid | C. Graphite |
| 4. Completes an electrochemical circuit | D. Protects from corrosion |
| 5. Electroplating benefit | E. Metal deposition on objects |
Answer:
| Column A | Correct Answer |
|---|---|
| 1. Process of electroplating | E. Metal deposition on objects |
| 2. Material used in electrodes | C. Graphite |
| 3. Role of sulfuric acid | A. Increases conduction |
| 4. Completes an electrochemical circuit | B. Salt bridge |
| 5. Electroplating benefit | D. Protects from corrosion |
