Page 159 - Science Class 08

1. What is the basic principle behind electropla ng?
2. What happens when electricity is passed through the copper sulphate solu on?

3. Why the rim of tyres are coated with chromium?
4. Write any two importance of electropla ng.

Electrolysis : The process of decomposition of solution into ions due to the effect of
electric current
Anode : Positive terminal of battery

Cathode : Negative terminal of battery
Electrolytes : Liquids that conduct electricity
Non-electrolytes : Liquids that do not conduct electricity

Ion : Charged atoms
Cations : Positively charged atoms
Anions : Negatively charged atoms

Electroplating : The process of coating a metal object with a thin layer of another metal
by means of electrolysis

Let's R
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I The solution which conducts electricity and undergoes decomposition is called electrolyte.
i The two rods or plates dipped in solution and connected to the battery are called electrodes.
i When electric current is passed through water, it decomposes into oxygen and hydrogen.
i Charged atoms are called ions.

i Positively charged ions are called cations and negatively charged ions are called anions.
i During electrolysis, ions with a positive electrical charge move towards the cathode and
whereas ions with a negative electrical charge move towards the anode.
i Electroplating is the process of coating a metal object with a thin layer of another metal by
means of electrolysis.
i Electroplating has so many usage.

Exercise
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A. Tick (3) the correct op on.
1. Which of the following conducts electricity?
(a) Kerosene (b) Alcohol
(c) Lemon juice (d) Milk

Science-8 159