Question

Class 8 Science MCQ Questions of Chemical Effects of Electric Current with Answers?

Answer 1

These Class 8 Science MCQ Questions of Chemical Effects of Electric Current with Answers will help understudies to go cover the whole part rapidly. By solving these questions understudies can acquire their certainty level while composing the last question paper. The MCQ Questions for class 8 gave here. It involves every one of the Questions that will assist understudies to elevate their score with point-by-point solutions. 

The significant Class 8 Science MCQ Questions of Chemicals Effects of Electric Current are made especially to help understudies and guide them in the right method of considering. In this section, the students will learn how various synthetics respond when an electric flow goes through them. Subsequent to perusing this part the Students will know which chemicals are good conductors of electricity and which one is a  poor conductor of electricity. Students are encouraged to solve Class 8 Science MCQ Questions of Chemicals Effects of Electric Current.

Practice Class 8 Science MCQ Questions chapter-wise

1. Which of the following is a bad conductor of electricity?

(a) Distilled water
(b) Silver nitrate
(c) Sulphuric acid
(d) Copper sulphate

2. Which of the following does not conduct electricity?

(a) Sugar solution
(b) Vinegar solution
(c) Lemon juice solution
(d) Caustic soda solution

3. An electric current can produce

(a) heating effect only.
(b) chemical effect only
(c) magnetic effect only
(d) chemical, heating, and magnetic effects

4. Pure or distilled water is a

(a) poor conductor
(b) good conductor
(c) both (a) and (b)
(d) none of these

5. Which of the following is a good conductor?

(a) Brick
(b) Steel
(c) Plastic
(d) Cotton

6. Polythene is

(a) a conductor
(b) an insulator
(c) both (a) and (b)
(d) none of these

7. Electroplating is based on

(a) heating effect of electricity
(b) chemical effect of electricity
(c) physical effect of electricity
(d) magnetic effect of electricity

8. Copper is

(a) a good conductor
(b) an insulator
(c) both (a) and (b)
(d) none of these

9. An electrolyte is

(a) a metal
(b) a liquid that conducts current
(c) a non-metal
(d) none of these

10. Flow of electron is called

(a) electrolyte
(b) electroplating
(c) electrodes
(d) electric current

11. Which is not a non-electrolyte?

(a) Glucose
(b) Acetic acid
(c) Urea
(d) Ethanol

12. An electric lamp glows due to

(a) heating effect
(b) magnetic effect
(c) chemical effect
(d) physical effect

13. Electroplating prevents

(a) corrosion
(b) passing of current
(c) dissociation
(d) shining

14. Which of the following metal is used in electroplating, in order to bring a shine to the objects?

(a) Zinc
(b) Chromium
(c) Copper
(d) Silver

15. In LEDs, the longer lead (wire) is always connected to the _______ terminal

(a) negative
(b) neutral
(c) positive
(d) Any terminal

16. When electrodes are immersed in water and electricity passed, the bubbles formed on the positive terminal are actually _______ gas.

(a) Hydrogen
(b) Carbon dioxide
(c) Oxygen
(d) Nitrogen

17. A coating of _________is deposited on iron to protect it from corrosion and the formation of rust

(a) copper
(b) aluminum
(c) Zinc
(d) silver

18. When electrodes are immersed in water and electricity passed, the bubbles formed on the negative terminal is actually _______ gas.

(a) Hydrogen
(b) Carbon dioxide
(c) Oxygen
(d) Nitrogen

19. Assertion: In electrolyte refining of metal, impure metal is made cathode while a strip of pure metal is used as an anode.

Reason: The pure metal gets deposited at the anode as anode mud. In electrolyte refining of metal, impure metal is made cathode while a strip of pure metal is used as an anode.

(a) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
(b) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
(c) Assertion is correct but Reason is incorrect
(d) Both Assertion and Reason are incorrect

20. The cans, used for storing food, are made by electroplating ……………. on to irons

(a) chromium
(b) zinc
(c) tin
(d) none of these

21. Adding lime water to tap water makes it:

(a) an electrolyte
(b) electrolysis
(c) no change occur
(d) none of these

22. The negative charged ions are called:

(a) cations
(b) anions
(c) ions
(d) none of these

23. Kerosene is:

(a) electrolyte
(b) non-electrolyte
(c) electrode
(d) none of these

24. Priya's uncle has set up an electroplating factory near his village. He should dispose of the waste of 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

25. Which one of the following solutions will not conduct electricity?

(a) lemon juice
(b) vinegar
(c) tap water
(d) vegetable oil

Answer 2

1. Answer: (a) Distilled water

Explanation: The availability of ions is very important to conduct electricity. Distilled water is a poor conductor of electricity because it can not provide ions to conduct electricity.

2. Answer: (a) Sugar solution

Explanation: The ions float freely through the liquid move towards electrodes of opposite charges and conduct electricity. Sodium hydroxide, lemon juice, and vinegar can ionize when due to passage of electric current but sugar solution does not ionize due to electric current. Sugar solution is not an electrolyte.

3. Answer: (d) chemical, heating, and magnetic effects

Explanation: An electric current can produce a magnetic effect on a moving charge as a current carrying wire generate a magnetic field in its surrounding.
Current can also produce a chemical effect like electrochemical reactions, it can also produce a heating effect as it generates heat in a resistance.

4. Answer: (a) poor conductor

Explanation: Pure or distilled water is a poor conductor of electricity.

5. Answer:Answer: (b) Steel

Explanation: Most metals conduct electricity to a certain extent. Some metals are more highly conductive than others. Copper, silver, aluminum, gold, steel, and brass are common conductors of electricity. The most highly conductive metals are silver, copper, and gold.

6. Answer: (b) an insulator

Explanation: An electrical insulator is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. Examples of insulators include glass, rubber, polythene, plastic, wood, and diamond.

7. Answer: (b) chemical effect of electricity

Explanation:  A direct current (DC) of electricity is passed through the solution, affecting the transfer of metal ions onto the cathode. So the transfer of ions from one electrode to another is because of the heating effect of the current and thus, electroplating is based on the chemical effect of electricity.

8. Answer: (a) a good conductor

Explanation: Copper is commonly used as an effective conductor in household appliances and in electrical equipment in general. Because of its low cost, most wires are copper-plated.

9. Answer: (b) a liquid that conducts current

Explanation:  An electrolyte is a  liquid or gel which contains ions and can be decomposed by electrolysis, i.e. that present in a battery. electrolyte conducts electricity by decomposing into its constituent ions.

10. Answer: (d) electric current

Explanation: Electricity is the flow of electrons through a conductor, usually in the form of a wire, this flow is called an electric current. Breaking the atomic bond between an electron and its nucleus requires an input of energy which causes the electron to overcome the electromagnetic force constraining it and thus flow freely.

11. Answer: (b) Acetic acid

Explanation: Acetic acid is a weak electrolyte because its dissociation constant is small meaning there will be few ions in solution to conduct electricity.

12. Answer: (a) heating effect

Explanation: The electric lamp glows because of the heating effect of the electric current. There is a relation between heat generated and the amount of electric current; it is given by the Joule's effect of heat.

13. Answer: (a) corrosion

Explanation: Electroplating is one of the most popular methods employed to achieve corrosion control. This metal coating acts as a sacrificial barrier that can slow and even prevent corrosion from forming on the underlying material, which is referred to as the substrate.

14. Answer: (b) Chromium

Explanation: Chromium is used in electroplating in order to bring a shine in the objects.

15. Answer: (c) positive

Explanation: Therefore, In an LED, the longer lead is always connected to the positive terminal of the battery and the shorter lead is connected to the negative terminal of the cell.

16. Answer: (c) Oxygen

Explanation: When electrodes are immersed in water and electricity passed the bubbles formed on the positive terminal is actually Oxygen gas..

17. Answer: (c) Zinc

Explanation: Galvanization is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanization, in which parts are submerged in a bath of molten zinc.

18. Answer: (a) Hydrogen

Explanation: When electrodes are immersed in water and electricity passed the bubbles formed on the negative terminal is actually Hydrogen gas.

19. Answer: (d) Both Assertion and Reason are incorrect

Explanation: In the Electrolytic refining method, the impure metal is made to act as anode. A strip of  same metal in pure form is used as cathode. They are put in a suitable electrolytic bath containing soluble salt of same metal. The more basic metal remains in the solution and less basic ones go to the anode mud. Copper is refined using an electrolytic method, anode of impure copper and pure copper strips are taken as cathode in the acidified copper sulphate solution. Impurities from the blister copper deposit as anode mud.

20. Answer: (c) tin

Explanation: Tin is a non-reactive metal whereas iron is a reactive metal. If food is stored in an iron container, it might react with iron and get spoiled. Hence, tin is electroplated on iron to make cans used for storing food. Electroplating tin makes the container non-reactive and look better.

21. Answer: (a) an electrolyte

Explanation: The substances that can dissociate into ions in water can act as electrolytes.Lime water is . It dissociates into and ions. Therefore, they act as electrolytes.

22. Answer: (b) anions

Explanation:  A negatively charged ion is known as an anion, as an anion is formed by the gain of one or more electrons by an atom.

23. Answer: (b) non-electrolyte

Explanation:  Electrolytes are the ionic substances while kerosene is a covalent substance hence it is not electrolyte.

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

Explanation: Waste disposal is a major concern in the electroplating industry as it causes water pollution and releases a hazardous chemical into water bodies. Hence it should be disposed of according to guidelines of the local authority.

25. Answer: (d) vegetable oil

Explanation: Vegetable oil does not contain ions hence it cannot conduct electricity.

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