Important Questions for CBSE Class 8 Science Chapter 14 Chemical Effects of Electric Current

Important Questions Class 8 Science Chapter 14 – Chemical Effects of Electric Current

Chapter 14 of CBSE Class 8 syllabus is about the Chemical Effects of Electric Current. This chapter explains some important topics, such as-

• Electricity in liquids.
• Chemical effects of electric current.
• Electrode.
• Electroplating.
• Good and bad conductors of electricity.
• LED.

Students studying science should start by going through the Class 8 Science NCERT textbook. Along with the textbook, it’s important to refer to NCERT exemplar books for solving chapter-specific questions. Science is a practical subject, so along with learning the theory , students can increase their understanding of the concepts by solving various questions from both the NCERT textbooks and exemplars. To get excellent grades in their assignments, tests, and exams  students must also go through Extramarks study materials, including NCERT solutions, CBSE chapter notes, and Important Questions Class 8 Science Chapter 14.

Extramarks thus provide students with a comprehensive list of important exam-oriented questions based on the CBSE syllabus. The Extramarks team refers to NCERT exemplars and textbooks, other important reference books, CBSE sample papers, CBSE past year’s question papers, etc., for collating the questions from all the chapters. Solving a lot of questions provided in our Important Questions Class 8 Science Chapter 14 can make the students feel prepared and confident to answer the different types of questions on their final exams.

Students are recommended to register on the Extramarks website to get access to our comprehensive study materials. They can avail the benefits of solving multiple problems from our solved question bank of Science Class 8 Chapter 14 Important Questions. Along with it, students can refer to other study materials, including NCERT solutions, revision notes, etc.

Get Access to CBSE Class 8 Science Important Questions 2022-23 with Chapter-Wise Solutions

You can also find CBSE Class 8 Science Chapter-by-Chapter Important Questions here:

Chemical Effects of Electric Current Class 8 Extra Questions with Solutions

Extramarks subject experts understand the importance of answering important questions, and we take our role seriously in providing students with the best resources to help them excel academically.Solving problems is one of the most beneficial tools for students who are preparing for mathematics and science exams. We recommend students refer to the Extramarks question bank of Important Questions for Class 8 Science Chapter 14. It is a comprehensive list of questions that will help students understand the exam format and question paper pattern. It comes with fully solved and step-by-step answers prepared by our expert faculty members. So students can use our question bank as a one-stop solution for all subjects to enhance their preparation.

Given below are a few questions and their solutions from our question set of Important Questions for Class 8 Science Chapter 14.

Question 1. What is the full form of the LED? 

1. Light Emitting Diode                               
2. Light Electricity Device 
3. Large Emitting Device                             
4. Large Electricity Diode 

Answer 1. A. Light Emitting Diode (LED) is a device that converts electrical energy into light energy.

Question 2. If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the __________terminal of the battery. 

1. Positive                               
2. Negative
3. Both                            
4. None of these

Answer 2. Option B. Negative terminal of the battery attracts Copper ions, and hence copper will get deposited on the plate

Question 3. Which one of the following is a good conductor of electricity? 

1. copper                                                        
2. wood 
3. distilled water                                           
4. none of these 

Answer 3. Option A. Copper is a good conductor of electricity.

Question 4. Electric current produces ______________field. 

1. chemical                                    
2. magnetic 
3. physical                                                   
4. complex 

Answer 4. Option B.

Electric current produces magnetic fields.

Question 5. Define electroplating. 

Answer 5. Electroplating is defined as the process of depositing a layer of any desired metal on another material by using electricity.

Question 6. Write one use of electroplating.

Answer 6. Electroplating is primarily used in industry to coat metal products with a thin layer of a different metal with greater value.

Question 7. Why rubber and plastics do not conduct electricity? 

Answer 7. Rubber and plastics do not allow electric current to pass through them. So they act as insulators and do not conduct electricity.

Question 8. Describe the functioning of a LED. 

Answer 8. The LED stands for light-emitting diode. It detects the weak current in a circuit. A LED has two wires, one wire is slightly longer than the other wire. The longer lead gets connected to the positive terminal of the battery. And the shorter lead gets connected to the negative terminal.

Question 9. Tap water is considered a good conductor of electricity. Why? 

Answer 9. Since tap water is not pure, it includes many mineral salts  such as dissolved sodium, calcium, and magnesium salts, naturally dissolved, making it a good conductor of electricity.

Question 10. Distilled water is a poor conductor of electricity. Justify. 

Answer 10. Distilled water is defined as the water in its purest form. So there are no traces of salts or other dissolved contaminants in pure distilled water. So distilled water is  a poor conductor of electricity.

Question 11. If a small amount of sugar is added to distilled water, will the resulting solution  be a good conductor or a poor conductor of electricity? Explain why. 

Answer 11. As a non-electrolyte material, sugar does not create ions when dissolved in water, making it a bad conductor of electricity. A sugar solution consists of sucrose molecules but no ions. An aqueous sugar solution is a non-electricity conductor fluid because it lacks ions.

Question 12. Fill in the blanks-

(a) Most liquids that conduct electricity are solutions of , ______________ and ______________.

(b) The passage of an electric current through a solution causes ______________ effects.

(c) If you pass current through the copper sulphate solution, copper gets deposited on the plate connected to the ___________terminal of the battery.

(d) The process of depositing a layer of any desired metal on another material using electricity is called _________.

Answer 12. (a) Most liquids that conduct electricity are the solutions of bases, acids and salts.

(b) The passage of electricity through a solution causes chemical effects.

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

(d) The process of depositing a layer of any desired metal on another material using electricity is called electroplating.

Question 13. When the free ends of the tester are dipped into a chemical solution, the magnetic needle shows deflection. Can you give  the reason?

Answer 13. The compass needle shows deflection, leading the current flow through the wire. The circuit becomes complete because the free ends of the tester are dipped inside the solution. So, the solution is a conducting solution; deflection is obtained in the compass needle.

Question 14. A tester is used to check the conduction of electricity through two liquids, A and B. It is found that the tester bulb glows brightly for liquid A and very dimly for liquid B. You would conclude that-

(a) liquid A is a better conductor than B.

(b) liquid B is a better conductor than A.

(c) both liquids are equally conducting.

(d) conducting properties of liquid should not be compared in this manner.

Answer 14. Liquid A is a better conductor as compared to liquid B.

Because the conductivity of the solution determines the amount of current flowing through the solution, the more the conductivity, the greater the quantity of current passing through the solution. The lesser the conductivity, the amount of passing a current through will correspond. Therefore, liquid A’s conductivity is more than liquid B..

Question 15. Can pure water be a conductor of electricity? If not, what can we do to make it a good conductor?

Answer 15. Pure water does not conduct any electricity as it does not contain any kind of salt. Adding some table salt (Sodium Chloride, i.e. NaCl) will change the water into a conducting medium.

Question 16. A child living in the coastal region tests the drinking water and seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason behind it?

Answer 16. The amount of salts dissolved in the seawater is more than that of the drinking water. So, seawater will be a better conductor than drinking water. This is the reason behind the increased deflection of the needle in the seawater compared to the drinking water.

Question 17. Prepare a list of things around you that are electroplated.

Answer 17. Chromium plating- This is done on exterior parts of automobiles to obtain a shiny appearance.

Gold Plating- Silver ornaments are coated with a thin layer of gold, and the product is called Gold-plated Ornaments.

Zinc Plating: Iron used for  construction is coated with a Zinc layer to protect them from corrosion and rusting.

Question 18. Is it safe for the electrician to do electrical repairs outdoors during heavy downpours? Explain.

Answer 18. No, It is not safe for one to repair electrical appliances outdoors during heavy downpours. Rainwater is composed of some amount of dissolved salts that make it conductive. This can cause electric shocks and harm the electrician while working outdoors during heavy downpours.

Question 19. An electric current can produce

(a) the heating effect only.

(b) the chemical effect only.

(c) the magnetic effect only.

(d) chemical, heating, and magnetic effects.

Answer 19. The answer is option (d) chemical, heating, and magnetic effects.

Explanation: Electric current causes a chemical reaction through a conducting solution. This shows the chemical effect of electric current.

When electricity passes through the bulb, its filament gets heated, and the bulb starts to glow. This shows the heating effect of electric current.

When electricity is passed through a circuit, it generates a magnetic field around it. This shows the magnetic effect of electric current.

Question 20. Boojho’s uncle has established an electroplating factory in his village. He should dispose waste of from the factory-

(a) in the nearby river.

(b) in the nearby pond.

(c) in the nearby cornfield.

(d) according to the disposal guidelines of the local authority.

Answer 20. The answer is option (d) according to the disposal guidelines of the local authority.

Explanation- Waste disposal is a significant concern in the electroplating industry as it causes water pollution and releases hazardous chemicals into water resources. Hence it should be disposed of as per the local authority’s guidelines.

Question 21. When an electric current is passed through a conducting solution, there is a change in the colour of the solution. This shows-

(a) the chemical effect of current.

(b) the heating effect of current.

(c) the magnetic effect of current.

(d) the lightning effect of current.

Answer 21. The answer is option (a) the chemical effect of current

Explanation- Conducting a solution through electric current causes  chemical reaction. This results in  a colour change, the electric current’s chemical effect.

Question 22. Paheli wants to coat silver on an iron spoon. She took some amount of silver nitrate (AgNO3) solution in a beaker and set up a simple circuit for electroplating. Explain which terminal of the battery the spoon should be connected to. What material should be used for the other electrode?

Answer 22. The spoon must be connected to the negative end of the battery. The other electrode should  be made of silver.

Question 23. Why is tin electroplated on iron to make the cans used for storing food?

Answer 23. Tin is less reactive than iron. To prevent iron from reacting with the food, tin is coated with  iron to make the can ideal for storing food.

Question 24. An electric current is passed into a conducting solution. What can be the three possible observations?

Answer 24. Few possible observations when electric current is passed through any conducting solution are.

i) Bubbles of gas can be formed on the electrodes and deposits of metal may also be seen on electrodes.

ii) The solution may get heated.

iii) There can be a change in the colour of the solution.

Question 25. In a circuit, Boojho observed that copper is deposited on the electrode connected to the battery’s negative terminal. Paheli also repeats the same experiment. But she finds only one copper plate. Therefore she takes a carbon rod as the negative electrode. Will copper still be deposited on the carbon rod? Explain your answer.

Answer 25. Copper from the copper sulphate(CuSO4) solution will be deposited on the carbon rod. Copper sulphate splits into copper and sulphate when an electric current is passed through the copper sulphate solution. The free copper gets drawn to the electrode connected to the battery’s negative terminal, i.e. carbon rod, and gets deposited on it. Thus, Paheli will obtain a layer of copper on a carbon rod.

Question 26. If the plus sign (+) denotes the positive electrode and the minus sign (-) indicates the negative electrode, then which of the following statements is correct for an iron spoon to be copper-plated?

(a) copper plate (-), Iron spoon (+), Iron sulphate electrolyte

(b) copper plate (+), Iron spoon (-), Iron sulphate electrolyte

(c) Copper-plate (-), iron spoon (+), copper sulphate electrolyte

(d) iron spoon (-), Copper Plated (+), copper sulphate electrolyte

Answer 26. Option (d) is the answer.

Question 27. Explain the process of electroplating with an experiment.

Answer 27. Copper sulphate and two copper plates are required. Take a clean and dry beaker, and pour around 250 ml of distilled water. Two spoons of copper sulphate should be dissolved in it. Add drops of dil. Sulphuric acid (H2SO4) to make the copper sulphate solution more conductible. Using sandpaper, clean the copper plates. After this, give them a good rinsing and allow them to air dry. Dip the copper plates in a copper sulphate solution after connecting them to both ends of a battery. Allow 15 minutes for the electric current to pass through it. Now, take the electrodes out and observe them closely. When an electric current is given to the solution, copper sulphate dissociates into copper and sulphate. The free copper metal is attracted to the electrode linked to the battery’s negative terminal and deposited there.

Question 28. Vinegar is a sour liquid state. Does vinegar conduct electricity or not?

Answer 28. Vinegar is a bad conductor of electricity because it has no free ions to carry an electric charge and conduct electricity.

Question 29. How would you classify lemon juice- as a good conductor or a poor conductor of electricity?

Answer 29. Lemon juice is a conductor of electricity because it has citric acid having positively charged ions responsible for the conduction.

Question 30. Write the name of a device which glows even when a weak electric current passes through it.

Answer 30. A Light Emitting Diode (LED) glows even if a weak current passes through it.

Question 31. What should be done to decompose water into hydrogen and oxygen?

Answer 31. We should pass an electric current into the water to decompose water into hydrogen and oxygen.

Question 32. Name the metal usually electroplated on car parts such as bumpers and bicycle handlebars made of steel.

Answer 32. Chromium metal is electroplated on car parts such as bumpers and bicycle/ motorcycle handlebars made of steel.

Question 33. What is the common use of the chemical effect of electric current?

Answer 33. The most common example of the chemical effect in electric currents is-

Gold plating and chromium metal plating prevent corrosion.

Question 34. Which is the polluting waste generated by electroplating factories?

Answer 34. The conducting solution which is used in the electroplating process is the final waste that is generated by electroplating factories.

Benefits of Solving Class 8 Science Chapter 14 Important Questions

Science syllabus of Classes 6, 7, 8 and 9 forms fundamental knowledge for higher classes. So students should focus on understanding the concepts of each topic in depth so that they have practical as well as  theoretical knowledge. A lot of practice and consistent effort must go towards understanding the core concepts of Science.

Our question bank of Important Questions Class 8 Science Chapter 14 is a comprehensive set of exam-oriented questions that are curated from various past years’ exam papers, NCERT exemplar and textbooks, and other Science reference books.

Extramarks believes in incorporating the best learning experiences through its own repository.To enjoy the maximum benefit of these resources, students just need to register themselves at Extramarks official website and stay ahead of the competition. Here we have given few benefits that students can  avail  by solving questions from our question bank of Important Questions Class 8 Science Chapter 14:

• The questions are curated and made from the exam point of view. Thus, students get exposure to real examinations while solving these questions. So it helps them to get rid of their fear factor and enhances their confidence while answering questions during  exams with greater accuracy. And speed..This helps them  to master the topic and increases their confidence in achieving a high grade.
• Important Questions Class 8 Science Chapter 14 offer students a comprehensive learning pattern to provide a smooth and deep learning experience to the students while solving questions of varying levels of difficulty.
• The list of  Important Questions Class 8 Science Chapter 14 includes a comprehensive list of questions from the entire chapter. So by properly solving all questions from the question bank students will be able to revise Chapter 14 fully. They would also be able to self-assess their readiness by comparing their answers with the given solutions. Based on this they can further work on their weaker sections.

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