NCERT Class VIII Science Solutions: Chapter 14-Chemical Effects of Electric Current Part 3

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Question 9:

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

Answer:

No it is very risky and unsafe to carry out electric repairs outdoors during heavy downpour. Water (when impure) is a good conductor of electricity and there are chances of getting electric shock.

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Electrical Repairs Outdoors

Question 10:

Paheli had heard that rainwater is as good as distilled water. So she collected some rainwater 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:

Air in our surroundings contains gasses, suspended dust particles and pollutants. These particles gets dissolved in rain water and make it good conducting medium of electricity.

Question 11:

Prepare a list of objects around you that are electroplated.

Answer:

Cold drink cans are tin plated. Artificial Jewellery items are silver or gold-plated. Car bumpers and cycle handles are chromium plated. Metal doors, door handles are zinc plated.

Question 12:

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 battery and why?

Answer:

Impure Copper plate should be connected to positive terminal. Pure copper plate should be connected to negative terminal of electrode as copper ions are positively charged and will attract to negative electrode terminal.

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