Class 8 Science Chapter 11 Important Question Answers - Chemical Effects of Electric Current

Q1: Why is it dangerous to touch an electrical appliance with wet hands?
Ans: It's dangerous because water is a conductor of electricity, and wet hands can provide a path for electric current to flow through your body, potentially causing electric shock.

Q2: How can you determine if a material is a good conductor of electricity using a tester?
Ans: You can determine if a material is a good conductor of electricity by using a tester. If the tester's circuit becomes complete and the bulb glows when the material is in contact with it, then the material is a good conductor.

Q3: Why do some liquids not allow electric current to pass even though they are conductive?
Ans: Some liquids may not allow electric current to pass effectively because their conductivity is weaker compared to metals. The current in the circuit may be too weak to make the bulb glow.

Q4: How can the magnetic effect of an electric current be used to create a tester for detecting weak currents?
Ans: The magnetic effect of an electric current can be used to create a tester by observing the deflection of a compass needle when current flows in a nearby wire. Even a small current will cause the compass needle to deflect.

Q5: Why is it preferable to classify materials as good conductors and poor conductors instead of conductors and insulators?
Ans: Most materials can conduct electricity under certain conditions, so it's more accurate to classify them as good conductors and poor conductors rather than just conductors and insulators.

Q6: What happens when salt is dissolved in distilled water concerning its conductivity?
Ans: When salt is dissolved in distilled water, it turns into a salt solution, which becomes a good conductor of electricity.

Q7: Which substances, when dissolved in distilled water, can make it conducting?
Ans: Most liquids that conduct electricity are solutions of acids, bases, and salts.

Q8: What are some of the chemical effects of electric current when it flows through a conducting solution?
Ans:  Chemical effects of electric current in a conducting solution can include the formation of gas bubbles on the electrodes, deposits of metal on the electrodes, and changes in the color of the solution.

Q9: What is electroplating, and why is it used?
Ans: Electroplating is the process of depositing a layer of one metal on top of another material using electricity. It is used to give objects desired properties that the base metal lacks, such as appearance, corrosion resistance, or durability.

Q10: How does electroplating work at the molecular level?
Ans: When electric current is passed through a solution containing a metal compound, the metal ions in the solution are reduced at the cathode (negative electrode) and get deposited on it, while an equal amount of metal from the anode (positive electrode) is oxidized and goes into the solution, maintaining a balance.

Q11: Why is chromium electroplated on various objects like car parts and bicycle handlebars?
Ans: Chromium is electroplated on these objects because it gives them a shiny appearance, corrosion resistance, and scratch resistance. Chromium is expensive, so only a thin layer is deposited over a cheaper base metal.

Q12: How does electroplating help in making cost-effective jewelry?
Ans: Jewelers electroplate less expensive metals like silver or gold onto other metals to create jewelry with the appearance of silver or gold, making it more affordable.

Q13: Why are tin cans for storing food made by electroplating tin onto iron?
Ans: Tin is less reactive than iron, so electroplating tin onto iron helps protect the food from coming into contact with iron, preventing spoilage.

Q14: Why is zinc electroplated onto iron in applications like bridges and automobiles?
Ans: Zinc is electroplated onto iron to protect it from corrosion and rust, as zinc is less reactive and provides a protective layer.

Q15: How does electroplating contribute to the durability and functionality of various metal objects in daily life?
Ans: Electroplating enhances the durability, appearance, and functionality of metal objects by providing them with properties that the base metal may lack, such as resistance to corrosion, wear, and aesthetic appeal.