Chemical effect of electric current Chapter 11 Extra Questions

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Short answer type questions:

Question 1
(i)What is a fire extinguisher? Write two types of fire extinguishers.
(ii)What is calorific value? Write its SI unit.
(iii)What are non-renewable fuels? Give two examples.
(iv)What are gaseous fuels? Give two examples.
(v)What is slow combustion? Give two examples.


(i)The fire extinguisher is a portable apparatus used to control the level of unwanted fire at a certain place. Two types of fire extinguishers are- carbon dioxide and soda-acid.
(ii)The efficiency of fuel that calculates the heat released when one gram of fuel burns completely in oxygen.
(iii)The fuels that are present in a limited amount are called non-renewable fuels. Coal and petroleum are two examples of non-renewable fuels.
(iv)The fuels that are found in the form of gaseous state are called gaseous fuels. Hydrogen and coal gas are two examples of gaseous fuels.
(v)The combustion that takes place slowly at a low temperature is called slow combustion. Digestion and rustling are two examples of slow combustion.

Short answer type questions/HOTS:

Question 2
Ron wants to place a battery inside a torch. How does he place the battery inside the torch?


Ron needs to place in such an order where positive terminal of the torch is attached to the negative terminal of the battery and the negative terminal of the torch is attached to the positive terminal of the battery.

Question 3
What is conventional current?


When the current flows from the positive terminal to the negative terminal in a closed circuit then it is known as conventional current.

Question 4
Ram tears the protective layer of the copper wire, which is made up of rubber, to connect it with the bulb. His son asked him a question that why do we cover the wires with the rubber?


Ram answered to his son that the wires are covered with the rubber because it is an insulator that cannot pass the electric current through it. Therefore, this rubber saves us from electric shock.

Question 5
What is an electrolyte?


Electrolyte is a liquid that conducts the electric current through it easily.

Question 6
(i)What is electrolysis?
(ii) In an open circuit, the switch is off. If Ola wants to switch on the light, she pressed the switch and the light is glowing now. How does the light glows?


(i)When we split the constituents of the liquid by the means of chemical effect of current. This method is called electrolysis.
(ii) When Ola pressed the switch, the open circuit converts into the closed circuit due to the complete flow of electric current in the circuit.

Question 7
Why metallic elements are good conduction of electricity?


Metallic elements have tendency to loss their free electrons that are present in their outermost orbits.

Question 8
What is electrical conductivity?


Electrical conductivity of a material is the tendency of conducting the electricity.

Long answer type questions:

Question 9
Explain the of electrolysis in water experiment. Draw a well-labelled diagram also.


  1. It is a process in which the constituents of water splits. The following procedure of the electrolysis are as follows: -
  2. Take 500 ml of jar and pour 300 ml of water in it.
  3. Add 25 cc Sulphuric acid in it.
  4. Place two rods in the jar and also connect them with a battery- one rod with positive terminal and another rod with a negative terminal of the battery.
  5. Cover the rods with test tubes.
  6. As the solution boils, the bubbles are formed in both the test tubes.
  7. The cathode forms hydrogen and the anode forms oxygen.
    Chemical effect of electric current  Class 8 Chapter 11 Extra Questions

Question 10
Explain electroplating in details.


  1. Electroplating works in the principle of electrolysis. It is a method of depositing a layer of material on other materials. It is important to do electroplating because it protects the materials from corrosion and also increase the durability of the material.
  2. On electroplating. The coated material with a layer is considered as anode while the material which is used for coating is treated as cathode. The salt solution that is same as cathode considers as electrolyte.
  3. Connecting with the source of electricity helps the electric current passes through the setup. Afterwards, the cations of the metals from the salt solution attract towards the cathode and get neutralised because of the presence of electrons.
  4. Consequently, the electrons move towards the anode and the neutral atoms of metal get accumulated on the surface of the cathode.
  5. The cations are transferred to the electrolyte, and these cations get deposited at the anode.
  6. As a result, a constant flow of cations is maintained from the anode to the cathode through electrolyte. Gradually, the coating is processed on the cathode.


This Chemical effect of electric current Extra Questions for Class 8 is prepared keeping in mind the latest syllabus of CBSE . This has been designed in a way to improve the academic performance of the students. If you find mistakes , please do provide the feedback on the mail.

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