NCERT solutions for Science [English] Class 8 chapter 11 - Chemical Effects of Electric Current [Latest edition]

Most liquids that conduct electricity are solutions of ________, _______ and ________.

The passage of an electric current through a solution causes ______ effects.

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

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

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

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

The bulb does not glow in the setup shown in figure list the possible reasons. Explain your answer.

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 ______.

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

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.

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?

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

Paheli had heard that rainwater 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?

Prepare a list of objects around you that are electroplated.

The process that you saw in the image 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 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?