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NCERT solutions Science Class 8 chapter 14 Chemical Effects of Electric Current


NCERT Science Class 8

Science Textbook For Class 8

Chapter 14 - Chemical Effects of Electric Current

Pages 180 - 181

Fill in the blanks.

Most liquids that conduct electricity are solutions of _______________ and ________

Q 1 | Page 180

Fill in the blanks

The passage of an electric current through a solution causes _________ effects

Q 1.2 | Page 180

Fill in the blanks

If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the __________ terminal of the battery.

Q 1.3 | Page 180

Fill in the blanks.

The process of depositing a layer of any desired metal on another material by means of electricity is called _________.

Q 1.4 | Page 180

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

Q 2 | Page 180

Name three liquids, which when tested in the manner shown in Figure, may cause the magnetic needle to deflect.

Q 3 | Page 180

The bulb does not glow in the setup shown in Figure List the possible reasons. Explain your answer.

Q 4 | Page 181

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

(1) liquid A is a better conductor than liquid B.

(2) liquid B is a better conductor than liquid A.

(3) both liquids are equally conducting.

(4) conducting properties of liquid cannot be compared in this manner.

Q 5 | Page 181

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

Q 6 | Page 181

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.

Q 7 | Page 181

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?

Q 8 | Page 181

Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Explain.

Q 9 | Page 181

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?

Q 10 | Page 181

Prepare a list of objects around you that are electroplated.

Q 11 | Page 181

The process that you saw in Activity 14.7 is used for purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from 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?

Q 12 | Page 181

NCERT Science Class 8

Science Textbook For Class 8