NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current

How does a bulb glow and give us light? This is because the filament in the bulb derives its heat from the heat in the current. How does the current pass. What are conductors of electricity? These are some of the interesting questions addressed in this chapter.

This chapter focuses on whether liquids can conduct electricity and why or why not. What is the chemical composition of liquids that enable electricity to pass through? They will perform some basic experiments to understand better.

Download PDF of NCERT Solutions for Class 8 Science Chapter 14

Question 1 - Fill in the blanks:

(a) Most liquids that conduct electricity are solutions of __________ , __________ and __________. (acids, bases, salts)
(b) The passage of an electric current through a solution cause__________effect. (chemical)
(c) If you pass current through copper sulfate solution, copper gets deposited on the plate connected to the __________terminal of the battery. (negative)
(d) The process of depositing a layer of any desired metal on another metallic object, by means of electricity, is culled __________. (electroplating)


Question 2 - When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?

Answer 2 - As the tester's free ends are dipped in a solution, the circuit becomes complete, causing the deflection. The solution has a conducting nature due to which compass needle is deflected.

Question 3 - Name three liquids, when tested in the manner shown in Figure, that may cause the magnetic needle to deflect.


Answer 3 - Tap water, salt solution, and vinegar can be three liquids that may cause the magnetic needle to deflect.


Question 4 - The bulb does not glow in the setup shown in Fig.14.10. List the possible reasons. Explain your answer.

Answer 4 – The possible reasons can be,

1. The bulb can be fused.
2. The solution is a poor conductor of electricity.
3. The wire is not conducting in nature.
4. Battery might be dead.
5. Wires might be loosely fitted.


Question 5 - A tester is used to check the conduction of electricity through two liquids, labelled A and B. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. You would conclude that

(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.

Answer 5 –


Question 6 - Does pure water conduct electricity? If not, what can we do to make it conducting?

Answer 6 - We can add salt to pure water to make it conduct. Because it lacks salt, it is a poor conductor of electricity as electricity does not conduct through pure water.

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NCERT Solutions for Class 8 Maths

Class 8 Maths Worksheets

Class 8 Maths Notes

Question 7- In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.

Answer 7 - As the water in water hoses contains salts, it is an excellent conductor of electricity. If the area's electrical supply isn't turned off before the firefighters spray the water, electricity could pass through the electrical appliances and harm them.

They turned off the power to avoid a situation like this.


Question 8 - A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?

Answer 8- The salt content of seawater is higher than that of drinking water. As a result, seawater is a better electrical conductor. This is why the compass needle deflects more in the presence of seawater.


Question 9 - Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpours? Explain.

Answer 9 - No, carrying out electrical repairs during a severe downpour is not safe for the electrician. It's because there's a bigger risk of electrocution during a severe downpour.


Question 10 - Paheli had heard that rain. water is as good as distilled water. So, she collected some rain water in a clean glass tumbler and tested it using a tester. To her surprise she found that the compass needle showed deflection. What could be the reasons?

Answer 10 - Rainwater is similar to distilled water, except it contains some contaminants from the atmosphere. Rainwater becomes conducting due to the presence of these contaminants. This is due to the deviation in the compass needle.


Question 11 - Prepare a list of objects around you that are electroplated.

Answer 11 – Objects around you that are electroplated.

1. Tire rims of vehicles
2. Door handles
3. Tin cans
4. Bottom of cooking utensils
5. Pots of metals, bath taps, ornaments


Question 12 - The process that you saw in Activity 14.7 is used for the purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from an impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?

Answer 12 - The copper plate rod should be attached to the battery's positive terminal. Because the copper sulphate solution dissociates into copper and sulphate when an electric current is passed through it. The free copper drawn to the battery's negative terminal gets deposited there. The copper lost in the solution, on the other hand, would be recovered from the impure copper rod connected to the battery's positive terminal.

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