Lakhmir Singh Manjit Kaur Class 8 Science 14th Chapter Chemical effects of electric current

Lakhmir Singh and Manjit Kaur Science solution: Chemical effects of electric current Chapter 14. Here you get easy solutions of Lakhmir Singh and Manjit Kaur Science solution Chapter 14 . Here we give Chapter 14 all solution of Class 8. Its help you to complete your homework.

Board – CBSE

Text Book – SCIENCE

Class – 8

Chapter – 14


1) Some liquids can conduct electricity.

2) Two liquid which conduct electricity are water and lemon juice.
Two liquid which not conduct electricity are distilled water and oil alcohol.

3) LED.

4) Light Emitting Diodes.

5) Lemon juice is a good conductor of electricity.

6) Vinegar is a acetic acid solution so it’s a good electricity conduct.

7) chemical effect.

8) Chemical effect.

9) a> Oxygen gas, b> Hydrogen gas.

(10) Electrolysis.

11) Electric current should be pass.

12) electroplating.

13) Chromium.

14) Tin.

15)  Bathroom taps; bicycle handlebars.

16) Electroplating.

17) Silver, Gold.

18) Electrolytes.

  1. Bicycle handlebars, bicycle bells, wheel rims, LPG stoves, Bathroom parts.

20) Copper, Zinc.

21) Sodium, aluminum.

22) Sodium.


24) a>True,  b> False.

25) a>Acid base, Salt, b>Low,  c> Chemical, d> Oxygen, Hydrogen, e> electroplating, f>Negative.


26) Liquids conduct electricity :

  • Lemon juice.
  • Vinegar.
  • Common salt solution.
  • Sulphuric acid solution.
  • Sea water.
  • Rain water.

Liquid do not conduct electricity :

  • Milk.
  • Sugar solution.
  • Honey.
  • Distilled water.

27) Water is a good conduct of electricity so it is dangerous to touch a electrical appliance with wet hands.

28) To detecting weak electric current.

29) a> Liquid effect of current     b> Magnetic effect of current.

30) Magnetic needle of compass will show deflection.

This is happen because a weak electric current flowing through a wire produce a magnetic field around it and this magnetic field of electric current acts on the magnetic needle of the compass and deflects it from its usual north-south position.

31) Distilled water is a poor conductor because it does not contain any dissolved salts on it, but tap water contains some minerals that’s why tap water conducts some electricity.

32) A small amount of salt can be added to distilled water in small amounts to make it a good conductor of electricity.

Salt solution is a good conductor of electricity. When salt dissolved, distilled water can be good conductor of electricity.

33) Sea water will be best conductor of electricity.

Sea water contains salt and salt solution is the good conductor of electricity.

34) Because of the chromium plating, new bicycle have shining handlebar and wheel rims.

If these are accidently scratched, the shiny chromium plating comes off and the iron or steel surface beneath it get exposed.

35) No, it is not safe for the electrician to carry out electrical repairs outdoors during heavy downpour.

Due to the presence of small amounts of acids in rainwater, It is being a conductor of electricity. It may cause electrocution of the electrician.

36) The solution conducts electric current. This electric current produces magnetic effect around the wire and deflects magnetic needle.

37) A red-brown layer of copper metal will be deposited on the carbon rod connected to the negative terminal of the battery. The carbon rod will be get copper-plated.

38) Pure water conduct a small amount of electricity.

If we mix small amount of salt, it will be conduct.

39) They cut off electricity supply for the area to prevent electrocution.

40) a> Electroplating.

b> Negative terminal of the battery is connected to the iron object.

The name of the electrolyte is Copper sulphate solution.

Long Answer Type Questions Answers

41) a> The materials which allow electric current to pass through them easily are called good conductors of electricity.

b> The application of chemical effects are :  Electroplating metals, Purification of metals.

c> The Chemical decomposition produced by passing an electric through a conducting liquid is called electrolysis.

42) The three substances are Acid, Bases and salts can produce a chemical effects

The filament in the bulb has resistance. The current flowing through the resistance of bulb causes the filament to dissipate energy in the form of heat and light. The filament is actually glowing white-hot because of the energy it is dissipating. This is how giving off light.

43) (a)The process of depositing a thin layer of a desired metal over a metal object with the help of electric current is called electroplating.

The purpose of electroplating is to protection against corrosion.

(b) For the shining appearance, Chromium metal make it suitable for electroplating.

Higher Order Thinking Skills (HOTS)


Pure water or distilled water is bad conductor electricity as they have no impurities or ions in them. In the drinking water the amount of salts dissolved in it is very less. On the other hand the amount of salt dissolved in sea water is very high. Due to the presence of large amount of dissolved salts in it sea water is a much better conductor of electricity than the drinking water.  The higher electric current passing through water produces stronger magnetic field in the wires that deflects the compass in the match box more.


There are some chemical effects of the electric current. The chemical effect produced by an electric current depends on the nature of conducting solution through which it is passed and on the nature of the electrodes used for passing the electric current. When an electric current is passed through a cut potato for a considerable time, we will notice a greenish – blue spot on the cut surface of the potato around the iron nail connected to the positive terminal of the battery. The formation of the spot shows that the chemical effect of current can bring about change in the color of conducting solution.


The Chemical effect of electric current is used in the purification of impure metals. To purify impure copper metal a solution of copper sulphate is used as electrolyte.The impure thick rod of copper is connected to the positive terminal of the battery and a thin strip of pure copper is connected to the negative terminal of the battery.


It is true that rainwater can be as pure as distilled water. However, in reality the while coming down the raindrops react with the acidic gases present in the air and produce acids. So if someone tests rain water using electrodes and compass then he can see deflections in the compass. This happens due to those acids present in the rain water.


In a clean glass beaker a solution is taken as electrolyte. Two terminals of a battery are submerged in the solution. Part of the connecting wire is wound around a compass. If the solution is good conductor of electricity then the compass will get deflected due to the magnetic field produced due to the electric flow in the wire.Examples of such solutions areVinegar, lemon juice and common salt solutions.

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