Chemical Effects of Electric Current
Each subtopic includes About section, revision page link, 10 preview questions, and practice CTAs.
Electrical Conductivity of Liquids
SubtopicElectrical Conductivity of Liquids under Chemical Effects of Electric Current for Grade 8 CBSE.
Preview questions (no answers)
- 1.
Which terminal of the battery is usually connected to the longer lead of an LED?
A.Negative
B.Positive
C.Neutral
D.Earth
- 2.
Is honey a good or poor conductor of electricity?
A.Good conductor
B.Poor conductor
C.Superconductor
D.It changes every minute
- 3.
Which of these is safe to use while handling electrical wires?
A.Iron tongs
B.Rubber gloves
C.Wet cloth
D.Copper pliers without insulation
- 4.
Which of the following is an example of a chemical effect of electric current?
A.The glowing of a bulb
B.The heating of an iron
C.Deposition of a metal on another
D.Deflection of a magnetic needle
- 5.
What is the correct dissociation equation for copper sulphate in an aqueous solution?
A.B.C.D. - 6.
When an electrolyte like copper sulphate () dissolves in water, it dissociates into:
A.Atoms
B.Molecules
C.Ions
D.Electrons
- 7.
In the process of galvanization, iron is coated with which metal to prevent rust?
A.Copper
B.Zinc
C.Silver
D.Gold
- 8.
Which of the following is NOT an application of the chemical effect of electric current?
A.Purification of metals
B.Electroplating
C.Production of heat in an electric toaster
D.Decomposition of compounds like water
- 9.
In an electroplating circuit, if we increase the number of batteries connected in series, what will happen to the amount of metal deposited on the cathode in a given time?
A.It will decrease.
B.It will increase because the current increases.
C.It will remain the same because the electrolyte is limited.
D.The metal will start falling off the cathode.
- 10.
Why are the handles of screwdrivers used by electricians usually made of plastic or wood?
A.Plastic and wood are stronger than metal.
B.Plastic and wood are insulators and prevent electric shock.
C.They provide a better grip than metal handles.
D.They prevent the screwdriver from becoming magnetized.
Download the worksheet for Chemical Effects of Electric Current - Electrical Conductivity of Liquids to practice offline. It includes additional chapter-level practice questions.
Chemical Changes during Electrolysis
SubtopicChemical Changes during Electrolysis under Chemical Effects of Electric Current for Grade 8 CBSE.
Preview questions (no answers)
- 1.
A student performs an activity by inserting two copper wires connected to a battery into a fresh potato. After some time, a greenish-blue spot is observed around the wire connected to the positive terminal. This change is a clear demonstration of the:
A.Magnetic effect of electric current
B.Heating effect of electric current
C.Chemical effect of electric current
D.Static effect of electric current
- 2.
Which of the following is a result of the chemical effect of electric current?
A.A glowing filament in a bulb
B.A rotating motor
C.Gas bubbles at the anode
D.Heating of a geyser
- 3.
In a copper sulphate solution experiment, which electrode loses copper?
A.The cathode
B.The anode
C.Both electrodes
D.The battery
- 4.
To test the conductivity of a liquid, the ends of the tester should:
A.Not touch each other
B.Touch each other
C.Be made of wood
D.Be painted
- 5.
When testing for the 'chemical effect' of current using a potato, the greenish-blue spot is caused by the reaction of which metal from the wire with the potato?
A.Iron
B.Copper
C.Silver
D.Aluminum
- 6.
What is the main advantage of using a tin coating over iron for storing food?
A.Tin is more reactive than iron
B.Tin is less reactive than iron and prevents food from contacting iron
C.Tin makes the iron stronger
D.Tin is much cheaper than iron
- 7.
If you reverse the battery terminals in an electroplating setup, what will happen?
A.The process will stop immediately
B.The metal will deposit on the opposite electrode
C.The battery will explode
D.The solution will catch fire
- 8.
Identify the false statement regarding the chemical effects of electric current.
A.Passage of current through a conducting solution causes chemical reactions
B.The effect depends on the nature of the solution and the electrodes
C.Only metals can act as electrodes in electrolysis
D.Electroplating is an application of the chemical effect of current
- 9.
What happens to the resistance of an electrolyte as the distance between the two electrodes is increased?
A.Resistance decreases
B.Resistance increases
C.Resistance remains the same
D.Resistance becomes zero
- 10.
Which of the following materials is most commonly used for the electrodes in the commercial production of aluminium by electrolysis?
A.Copper
B.Iron
C.Carbon (Graphite)
D.Silver
Download the worksheet for Chemical Effects of Electric Current - Chemical Changes during Electrolysis to practice offline. It includes additional chapter-level practice questions.
Process and Applications of Electroplating
SubtopicProcess and Applications of Electroplating under Chemical Effects of Electric Current for Grade 8 CBSE.
Preview questions (no answers)
- 1.
Is the process of electroplating used for purifying metals?
A.Yes, it is a common application
B.No, it is only for decoration
C.No, it is only for making magnets
D.Yes, but only for plastic
- 2.
Which of the following is used for electroplating to prevent corrosion of iron?
A.Oxygen
B.Nitrogen
C.Zinc
D.Sulphur
- 3.
What happens to the copper atoms when they reach the cathode during copper plating?
A.They turn into gas
B.They gain electrons and become copper metal
C.They dissolve into the solution
D.They disappear
- 4.
Which property of tin makes it suitable for coating iron containers used for food?
A.It is very magnetic
B.It is more reactive than iron
C.It is less reactive than iron
D.It is a liquid at room temperature
- 5.
In a copper plating experiment, which electrode is 'sacrificial', meaning it gradually wears away to provide metal ions?
A.The Cathode
B.The Anode
C.Both electrodes
D.Neither electrode
- 6.
Which of the following liquids is usually a good conductor of electricity?
A.Honey
B.Lemon juice
C.Vegetable oil
D.Distilled water
- 7.
During the chemical effect of current, if the electrodes are immersed in a solution of a metal salt, where is the metal usually deposited?
A.On the electrode connected to the positive terminal
B.On the electrode connected to the negative terminal
C.At the bottom of the beaker
D.On the surface of the solution
- 8.
In an experiment, if the current is kept constant but the temperature of the electrolyte is significantly raised, what is a likely effect on the process?
A.The conductivity of the electrolyte will generally increase, potentially changing the plating quality.
B.The ions will move slower due to increased molecular collisions.
C.The metal ions will evaporate before reaching the cathode.
D.The battery voltage will automatically double.
- 9.
A student attempts to plate an object using a solution of distilled water and table salt (NaCl) with copper electrodes. What will be the primary observation at the cathode?
A.A thick, shiny layer of copper.
B.A layer of silver-colored sodium metal.
C.Evolution of hydrogen gas and no copper plating.
D.The water will turn into solid ice.
- 10.
Why is 'Passivation' sometimes required after an object has been electroplated?
A.To make the metal more magnetic.
B.To create a thin, protective oxide film on the surface to further enhance corrosion resistance.
C.To remove the electric charge from the object so it can be touched.
D.To dissolve the plating so the object can be reused.
Download the worksheet for Chemical Effects of Electric Current - Process and Applications of Electroplating to practice offline. It includes additional chapter-level practice questions.