Chemical Effects of Electric Current – MCQs with Answers and Explanations
CBSE Class 8 Science – Chapter Wise Study Materials Based on NCERT
Chapter 14: Chemical Effects of Electric Current – 50 MCQs with Answers & Explanations
Suitable for:
Annual Examination • Periodic Tests • Class Tests • Pre-Board / School Level Board Exam Pattern
These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 8 board exams standard.
Below is a comprehensive, topic-wise set of 50 MCQs from
Chapter 14: Chemical Effects of Electric Current with answers and concept-clearing explanations
to support effective revision and exam preparation.
Topic-wise MCQs – Chapter 14: Chemical Effects of Electric Current
Topic 1 – Conductors, Insulators & Conducting Liquids (Q1 – Q10)
Q1. A conductor is a substance which:
Correct Answer: (B)
A conductor has free electrons or ions that allow electric current to pass easily. Metals and some liquids are conductors.
Q2. Which of the following is an insulator?
Correct Answer: (C)
Plastic does not allow electric current to pass through it easily and is used to cover wires, so it is an insulator.
Q3. Which of the following liquids is a good conductor of electricity?
Correct Answer: (C)
Lemon juice contains acid and ions which allow current to pass, so it is a good conductor among the given options.
Q4. Which statement about distilled water is correct?
Correct Answer: (B)
Pure distilled water has almost no dissolved salts or ions, so it is a very poor conductor of electricity.
Q5. Tap water conducts electricity mainly due to the presence of:
Correct Answer: (C)
Dissolved salts and minerals form ions in tap water, which carry electric charge and make it conducting.
Q6. Which of the following pairs contains only poor conductors of electricity?
Correct Answer: (C)
Kerosene and cooking oil do not form ions and thus do not conduct electricity; they are poor conductors/insulators.
Q7. Which statement is true for sugar solution in water (in small amount)?
Correct Answer: (C)
Sugar does not form ions in water, so sugar solution in small amount behaves almost like a non-conductor of electricity.
Q8. The human body is considered a conductor because:
Correct Answer: (B)
Body fluids contain water with dissolved salts and ions that allow electric current to pass through the human body.
Q9. Which combination is most likely to behave as insulators?
Correct Answer: (C)
Plastic and glass do not allow electric current to pass easily; they are commonly used as insulating materials.
Q10. A conducting liquid is one which:
Correct Answer: (B)
Conducting liquids (electrolytes) contain ions that can move and carry electric charge under a potential difference.
Topic 2 – Testing Conductivity: LED, Bulb & Magnetic Effect (Q11 – Q18)
Q11. In the activity to test liquids, which device is most sensitive to detect weak current?
Correct Answer: (C)
An LED can glow even with a very small current, so it is more sensitive than a filament bulb for detecting weak conduction in liquids.
Q12. A bulb does not glow when electrodes are dipped in a solution. It means:
Correct Answer: (C)
The solution may conduct weakly, but the current may not be sufficient to heat the filament and make it glow. An LED test is better in such cases.
Q13. The deflection of a compass needle near a coil in the circuit shows that:
Correct Answer: (C)
A current-carrying coil produces a magnetic field that deflects a nearby compass needle. This shows that current is flowing in the circuit.
Q14. Which of the following is NOT needed in a simple circuit to test the conductivity of a liquid?
Correct Answer: (D)
A transformer is not required for a small testing circuit; a battery, indicator (bulb/LED), wires and electrodes are enough.
Q15. In a test circuit, two electrodes dipped in a liquid touch each other. The likely result is:
Correct Answer: (B)
If electrodes touch, current bypasses the liquid and may produce a short circuit, which is unsafe and spoils the activity.
Q16. In a school activity, the LED glows only when the compass needle deflects. This shows that:
Correct Answer: (B)
Both LED glow and compass deflection are caused by electric current, showing that current can produce heating, magnetic and chemical effects together.
Q17. Why are electrodes cleaned before using them in conductivity experiments?
Correct Answer: (C)
Cleaning removes dirt, rust or grease, ensuring proper contact with the solution and accurate testing of conductivity and chemical effects.
Q18. An advantage of using a compass needle in conductivity tests is that it:
Correct Answer: (B)
A compass needle is very sensitive to magnetic fields, so it can show even small currents by deflection, which helps in weak conductivity tests.
Topic 3 – Chemical Effects of Electric Current & Key Terms (Q19 – Q26)
Q19. The chemical changes produced in a conducting solution due to electric current are called:
Correct Answer: (C)
When current passes through certain liquids, they undergo chemical changes such as gas formation and metal deposition; these are chemical effects of electric current.
Q20. The conducting solution used in an electrolytic cell is called:
Correct Answer: (B)
The liquid or solution through which current passes in an electrolytic cell is called the electrolyte; it contains ions and conducts electricity.
Q21. The electrodes in an electrolytic cell are usually made of:
Correct Answer: (B)
Electrodes must conduct electricity, so they are generally made of metals like copper, zinc or graphite (carbon rods).
Q22. The electrode connected to the positive terminal of the battery is called:
Correct Answer: (B)
The electrode connected to the positive terminal is the anode; to the negative terminal is the cathode.
Q23. The electrode where positive ions gain electrons and get deposited is called:
Correct Answer: (D)
Positive ions move towards the negative electrode (cathode), gain electrons and deposit there as neutral atoms or metal.
Q24. During the chemical effect of electric current, which of the following may NOT be observed?
Correct Answer: (D)
Chemical effects may show gas formation, colour change or metal deposition. Formation of ice cubes is unrelated to chemical effects of current.
Q25. Electrolysis means:
Correct Answer: (B)
Electrolysis is the process in which an electric current causes a compound in solution to break down into simpler substances or elements.
Q26. In an electrolytic solution, the carriers of electric charge are:
Correct Answer: (C)
In liquids, electric current is mainly carried by ions (positively and negatively charged particles) moving through the solution.
Topic 4 – Copper Sulphate Activity & Related Concepts (Q27 – Q34)
Q27. In the copper sulphate experiment with copper electrodes, the blue colour of the solution remains almost unchanged because:
Correct Answer: (C)
Copper atoms leave the anode as Cu²⁺ ions and an equal number of Cu²⁺ ions deposit on the cathode, so the concentration and colour remain nearly constant.
Q28. In the same experiment, the electrode connected to the negative terminal:
Correct Answer: (B)
The negative electrode is the cathode; Cu²⁺ ions from the solution gain electrons there and deposit as copper, increasing its mass.
Q29. When iron is dipped in copper sulphate solution with current passing, copper deposits on iron because:
Correct Answer: (C)
Cu²⁺ ions in the solution move to the cathode (iron piece), gain electrons and deposit as copper metal, forming a reddish-brown layer on iron.
Q30. In the copper sulphate experiment with copper electrodes, what happens at the anode?
Correct Answer: (B)
At the anode, copper atoms lose electrons and go into the solution as Cu²⁺ ions, making the anode thinner over time.
Q31. Which of the following is NOT correct for the copper sulphate experiment?
Correct Answer: (C)
The concentration of Cu²⁺ ions does not always increase; it remains nearly steady because ions leaving and depositing balance each other when both electrodes are copper.
Q32. The blue colour of copper sulphate solution is due to:
Correct Answer: (B)
The characteristic blue colour of CuSO₄ solution comes from Cu²⁺ ions present in the solution.
Q33. Changing one of the copper electrodes to carbon in CuSO₄ solution will:
Correct Answer: (C)
With only one copper electrode, Cu²⁺ ions are removed from the solution to deposit on the copper/cathode, so the blue colour slowly fades over time.
Q34. The copper sulphate experiment mainly shows that:
Correct Answer: (C)
The experiment demonstrates that electric current passing through a liquid (CuSO₄ solution) can cause chemical changes such as metal deposition and dissolution.
Topic 5 – Electroplating: Principle, Uses & Examples (Q35 – Q44)
Q35. Electroplating is the process of:
Correct Answer: (B)
Electroplating uses the chemical effect of electric current to deposit a thin layer of one metal onto another metal object.
Q36. In electroplating, the object to be plated is always made the:
Correct Answer: (B)
The object is connected to the negative terminal and acts as the cathode, where positive metal ions deposit and form a coating.
Q37. For copper electroplating, which electrolyte is commonly used?
Correct Answer: (B)
Copper sulphate solution contains Cu²⁺ ions needed to deposit copper on the cathode during electroplating.
Q38. Which arrangement is correct for electroplating an iron key with copper?
Correct Answer: (B)
The object to be plated (iron key) is cathode, the source metal (copper strip) is anode, and the electrolyte is copper sulphate solution containing Cu²⁺ ions.
Q39. The main purpose of electroplating steel spoons with silver is to:
Correct Answer: (C)
Silver plating gives a shiny, attractive appearance and a non-reactive surface, protecting the steel spoons and reducing corrosion.
Q40. Why are cycle and car parts often chrome-plated?
Correct Answer: (C)
Chromium provides a shiny, hard and corrosion-resistant coating, so chrome plating is used to protect and beautify vehicle parts.
Q41. Electroplating helps save expensive metals because:
Correct Answer: (B)
Only a thin outer layer of an expensive metal like gold or chromium is deposited on a cheap base metal, saving a large amount of costly metal.
Q42. Cleaning the object before electroplating is important because:
Correct Answer: (B)
Dust, grease or rust prevent proper sticking of the new metal layer. Cleaning ensures a smooth, strong and uniform electroplated coating.
Q43. Which of the following is NOT a correct use of electroplating?
Correct Answer: (D)
Heating in a flame is not electroplating. Electroplating always involves electricity and an electrolytic solution to deposit a metal coating.
Q44. During electroplating of an object, the mass of the cathode:
Correct Answer: (C)
At the cathode, metal ions gain electrons and deposit as metal, increasing the cathode’s mass and forming the electroplated layer.
Topic 6 – Safety, Higher-Order & Mixed Application Questions (Q45 – Q50)
Q45. It is dangerous to touch electrical appliances with wet hands because:
Correct Answer: (A)
Water with dissolved salts is conducting. Wet skin offers less resistance, allowing more current to pass through the body, which can cause electric shock.
Q46. School experiments on chemical effects of current use cells or small batteries instead of mains supply because:
Correct Answer: (C)
Batteries give low voltage and limited current, making experiments safer for students compared to high-voltage mains electricity.
Q47. A student concludes that a solution is a non-conductor because the bulb did not glow. This conclusion may be wrong because:
Correct Answer: (B)
The bulb needs sufficient current to glow. A weakly conducting solution may not light the bulb but may still conduct a small current detectable by an LED or compass test.
Q48. Which of the following changes clearly represents a chemical effect of electric current?
Correct Answer: (C)
Metal deposition involves formation of a new substance and is a chemical change caused by the passage of electric current through an electrolyte.
Q49. Which of these best describes an electrolyte?
Correct Answer: (B)
Electrolytes are liquids/solutions containing ions and can conduct electricity due to movement of these ions, such as salt solutions and acids.
Q50. The study of chemical effects of electric current is important because it helps us understand:
Correct Answer: (C)
Chemical effects explain important applications like electroplating, electrolysis and purification of metals, which are widely used in industries and daily life.
These 50 topic-wise MCQs with answers and explanations cover all major concepts, activities and applications
from Chapter 14: Chemical Effects of Electric Current of NCERT Class 8 Science,
helping students prepare thoroughly for CBSE Class 8 board exam standard.