Extra 40 multiple-choice questions (MCQs) "Chemical Effects of Electric Current" chapter:11 of Class 8 CBSE Science:-
Which of the following liquids is a good conductor of electricity?
(a) Distilled water
(b) Sugar solution
(c) Salt solution
(d) Kerosene
Answer: (c) Salt solution
The process of depositing a layer of metal on another material by means of electricity is called:
(a) Electrolysis
(b) Electroplating
(c) Magnetism
(d) Conduction
Answer: (b) Electroplating
Which gas is evolved at the cathode during the electrolysis of water?
(a) Oxygen
(b) Hydrogen
(c) Chlorine
(d) Nitrogen
Answer: (b) Hydrogen
Which of the following is a poor conductor of electricity?
(a) Copper
(b) Silver
(c) Rubber
(d) Iron
Answer: (c) Rubber
The liquid that conducts electricity is called:
(a) Insulator
(b) Conductor
(c) Electrolyte
(d) Semiconductor
Answer: (c) Electrolyte
In electroplating, the object to be coated is connected to the:
(a) Positive terminal of the battery
(b) Negative terminal of the battery
(c) Neutral terminal
(d) Any terminal
Answer: (b) Negative terminal of the battery
What is the full form of LED?
(a) Light emitting device
(b) Light energy diode
(c) Light emitting diode
(d) Liquid emitting diode
Answer: (c) Light emitting diode
Which effect of electric current is used in electroplating?
(a) Heating effect
(b) Magnetic effect
(c) Chemical effect
(d) Light effect
Answer: (c) Chemical effect
Distilled water is a:
(a) Good conductor
(b) Poor conductor
(c) Semiconductor
(d) Superconductor
Answer: (b) Poor conductor
The electrodes in an electrolytic cell are:
(a) Conductors
(b) Insulators
(c) Semiconductors
(d) Dielectrics
Answer: (a) Conductors
Which of the following is used to purify metals?
(a) Electroplating
(b) Electrolysis
(c) Magnetism
(d) Heating
Answer: (b) Electrolysis
The positive electrode in an electrolytic cell is called:
(a) Cathode
(b) Anode
(c) Neutral electrode
(d) Ground electrode
Answer: (b) Anode
The negative electrode in an electrolytic cell is called:
(a) Anode
(b) Cathode
(c) Neutral electrode
(d) Ground electrode
Answer: (b) Cathode
Which metal is commonly used for electroplating iron to prevent rusting?
(a) Copper
(b) Silver
(c) Zinc
(d) Gold
Answer: (c) Zinc
The flow of electric current through a conducting solution
causes
:
(a) Physical changes
(b) Chemical changes
(c) Magnetic changes
(d) No changes
Answer: (b) Chemical changes
Which of the following liquids is a good electrolyte?
(a) Kerosene
(b) Petrol
(c) Lemon juice
(d) Distilled water
Answer: (c) Lemon juice
What is the purpose of electroplating chromium on car parts?
(a) To increase conductivity
(b) To prevent corrosion
(c) To increase magnetism
(d) To increase temperature
Answer: (b) To prevent corrosion
The presence of which ions makes water a good conductor?
(a) Hydrogen ions
(b) Oxygen ions
(c) Dissolved salts
(d) Carbon dioxide
Answer: (c) Dissolved salts
What happens when an electric current is passed through copper
sulphate
solution?
(a) Copper is deposited on the anode
(b) Copper is deposited on the cathode
(c) Oxygen is released
(d) No change occurs
Answer: (b) Copper is deposited on the cathode
Which of the following is an application of electrolysis?
(a) Heating a room
(b) Electroplating
(c) Lighting a bulb
(d) Generating magnetic fields
Answer: (b) Electroplating
What is the purpose of using a magnetic compass in testing for electric current in a solution?
(a) To measure voltage
(b) To detect magnetic field produced by the current
(c) To measure resistance
(d) To measure temperature
Answer: (b) To detect magnetic field produced by the current
Pure water is a poor conductor of electricity because it:
(a) Has high resistance
(b) Has low resistance
(c) Does not contain ions
(d) Is a non-metal
Answer: (c) Does not contain ions
Which of the following is used in the purification of copper?
(a) Electroplating
(b) Electrolytic refining
(c) Magnetism
(d) Heating
Answer: (b) Electrolytic refining
The process of decomposition of a chemical compound by passing electric current is called:
(a) Electroplating
(b) Electrolysis
(c) Magnetism
(d) Heating
Answer: (b) Electrolysis
Which gas is evolved at the anode during the electrolysis of water?
(a) Hydrogen
(b) Oxygen
(c) Nitrogen
(d) Carbon dioxide
Answer: (b) Oxygen
Which of the following is a good conductor?
(a) Plastic
(b) Wood
(c) Graphite
(d) Rubber
Answer: (c) Graphite
What is the purpose of coating iron with tin in food cans?
(a) To increase strength
(b) To prevent food from reacting with iron
(c) To increase conductivity
(d) To increase magnetism
Answer: (b) To prevent food from reacting with iron
What is the effect of electric current on a conducting solution?
(a) Heating effect
(b) Magnetic effect
(c) Chemical effect
(d) All of the above
Answer: (d) All of the above
Which of the following is used in the extraction of metals?
(a) Electroplating
(b) Electrolysis
(c) Magnetism
(d) Heating
Answer: (b) Electrolysis
Which device is used to detect weak currents?
(a) Voltmeter
(b) Ammeter
(c) LED
(d) Thermometer
Answer: (c) LED
What type of change takes place during electroplating?
(a) Physical change
(b) Chemical change
(c) No change
(d) Magnetic change
Answer: (b) Chemical change
What is the purpose of electroplating?
(a) Decoration
(b) Corrosion prevention
(c) Both a and b
(d) None of the above
Answer: (c) Both a and b
Which of the following is an example of an electrolyte?
(a) Petrol
(b) Kerosene
(c) Copper
sulphate
solution
(d) Dry wood
Answer: (c) Copper
sulphate
solution
What is the role of electrodes in electrolysis?
(a) To heat the solution
(b) To conduct electricity into the solution
(c) To cool the solution
(d) To filter the solution
Answer: (b) To conduct electricity into the solution
The deposition of metal on the cathode during electrolysis is due to:
(a) Oxidation
(b) Reduction
(c) Neutralization
(d) Evaporation
Answer: (b) Reduction
Which of the following materials is used for making electrical wires?
(a) Plastic
(b) Rubber
(c) Copper
(d) Wood
Answer: (c) Copper
What is the purpose of using zinc coating on iron?
(a) To make it shiny
(b) To prevent rusting
(c) To increase its weight
(d) To make it magnetic
Answer: (b) To prevent rusting
The chemical effect of electric current is related to:
(a) Heating
(b) Magnetism
(c) Electrolysis
(d) Light emission
Answer: (c) Electrolysis
What is the process of using electric current to separate metals from their ores?
(a) Electroplating.
(b) Electrolytic refining.
(c) Electrolysis.
(d) Galvanization.
Answer: (c) Electrolysis
In an LED, the longer lead is connected to the:
(a) Negative terminal
(b) Positive terminal
(c) Neutral terminal
(d) Ground terminal
Answer: (b) Positive terminal
