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Want to know how electric current can even split water? Class 8 Science Chapter 11 Chemical Effects of Electric Current introduces students to fundamental concepts of electricity and its chemical effects, which are vital in understanding more complex topics like current electricity, electrochemistry, and more. The NCERT solutions of class 8 science by Careers360 professionals make you understand these awesome concepts easily and understand their practical uses.
NCERT Solutions of Chemical Effects of Electric Current includes 12 questions on the different activities given in the chapter. Here you will find detailed and easy-to-understand solutions that help prepare for exams. You can view the topics covered in this chapter at a glance, as well as the important concepts learnt. Also, find the guide to learning the chapter and the crucial points to remember under the approach to solve NCERT questions. Chapter 11 of the NCERT Solutions Class 8 plays a pivotal role in laying a strong foundation for higher classes, particularly in the field of physics and chemistry. Students can also find the links to the NCERT solutions of other chapters of class 8 below.
Download the free PDF of NCERT Solutions for Class 8 Science Chapter 11 – Chemical Effects of Electric Current. It is suitable for offline access and last-minute revision.
Q1. Fill in the blanks.
(a) Most liquids that conduct electricity are solutions of acids, bases and salts.
(b) The passage of an electric current through a solution causes chemical effects.
(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the negative terminal of the battery.
(d) The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating.
The magnetic needle shows deflection and therefore current must be flowing through the circuit. The circuit is complete and therefore the solution is electrically conducting due to the presence of charged particles called ions.
Three liquids which may cause the magnetic needle to deflect when tested in the manner shown in Fig 10.9 are lemon juice, salt solution and vinegar.
The bulb might not glow due to the following reasons:
(a) The liquid might not be a conductor of electricity.
(b) The current might be very weak and not sufficient enough to light the bulb, this could happen due to the battery not being charged or because of the circuit being poorly conducting.
(i) liquid A is a better conductor than liquid B.
(ii) liquid B is a better conductor than liquid A.
(iii) both liquids are equally conducting.
(iv) conducting properties of liquid cannot be compared in this manner.
(i) liquid A is a better conductor than liquid B.
The brightness of the bulb depends on the current flowing through it which in turn depends on the conductivity of the liquid. Since the brightness of the bulb is more in case of liquid A we conclude liquid A is a better conductor than liquid B.
Q6. Does pure water conduct electricity? If not, what can we do to make it conducting?
No, pure water does not conduct electricity because of the absence of charged particles known as ions which facilitate conduction of electricity. To make it conducting we can add salt, acid or base to the water.
As we know water is a conductor of electricity, the poured water may come in contact with some electrical appliance or electrical cable causing the current to reach the firemen and harm them. Thus to avoid this the main electrical supply for the area is shut down before the firemen use the water hoses.
Seawater is salty and as we know salt imparts the property of electrical conduction to water, it will be more conducting than drinking water which has a lesser amount of dissolved salt than seawater. Due to higher electrical conductivity, the deflection of the needle is more in the case of seawater.
No, it is not safe for the electrician to carry out electrical repairs outdoors during a heavy downpour as rainwater contains dissolved salts which makes rainwater a good conductor of electricity and due to this the electrician might get an electric shock while working outdoors during a heavy downpour.
The reason behind the needle showing deflection in case of rainwater is the fact that rainwater has dissolved salts in it which makes it a good conductor of electricity whereas distilled water is completely devoid of any salts and does not conduct electricity.
Q11. Prepare a list of objects around you that are electroplated.
List of objects which are electroplated around us:
(i) Gold is electroplated on ornaments.
(ii) Zinc is electroplated on pipes and machinery.
(iii) Chromium is electroplated on parts of vehicles.
(iv) Tin is used to coat metal containers for food.
Copper ions carry a positive charge and would be attracted towards the negative terminal. Since we want to transfer copper from the thick impure copper rod to the thin copper strip, the thick copper rod should be connected to the positive terminal of the battery and consequently the thin copper strip to the negative terminal of the battery.
Topics for class 8 chemical effects of electric current NCERT solutions are listed below:
Flow of electrons through a conductor.
Materials like copper and aluminium that allow current to pass through.
Materials like rubber and plastic that do not allow current to pass through.
A simple method to test if a liquid conducts electricity.
A test utilising the magnetic effect of current by checking if a compass needle is deflected.
A liquid that conducts electricity and undergoes chemical changes.
A process where a metal is coated on another material using electric current.
Change in colour of the solution
Formation of gas bubbles
Deposition of metal on electrodes
Heating effect in some cases
Electroplating of metals
Understanding electricity and the properties of conductors and insulators is essential for this chapter. This includes testing for the flow of current, using its magnetic effect to see deflection in a compass needle or by connecting a light source like a bulb or an LED to the circuit. It is important to learn what makes liquids conduct electricity and the requirements to do so. Finally, we understand the chemical reactions that can occur when current is passing and its practical application, such as electroplating. It is important to learn about different materials and liquids, and note the effect of electricity on them.
The chapter-wise NCERT solutions for all the science chapters are listed here along with their links:
Electroplating is the chemical process of covering an object with a thin layer of metal by electrochemical disposition
Here are the topics covered in NCERT Class 8 Science chapter 11
Chapter 11 "Chemical Effects of Electric Current" is important for exams as it covers the concepts of electroplating, electrolysis, and how electricity can bring about chemical changes in substances. A thorough understanding of this chapter is essential for students interested in pursuing higher studies in science and for performing well in competitive exams.
Electrolytes are liquids that can conduct electricity. These are usually solutions of acids, bases and salts.
To test if electricity is flowing, you can use the LED glowing test or the compass needle test.
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