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    8th Chemical Effects of Electric Current Solved Questions

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    Kavitha K
    This document contains 16 questions and answers about the chemical effects of electric current. Some key points covered include: - Liquids that are conductors of electricity include lemon juice, vinegar, salt solution, sea water, and rain water. Non-conductors include milk, distilled water, and honey. - LEDs are better than light bulbs for testing liquid conductivity because LEDs glow with weak currents while bulbs may not heat up enough. - When passing current through a solution, the magnetic effect deflects a compass needle while the heating effect causes a bulb to glow.

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    8th Chemical Effects of Electric Current Solved Questions

    Uploaded by

    Kavitha K
    61 views3 pages
    This document contains 16 questions and answers about the chemical effects of electric current. Some key points covered include: - Liquids that are conductors of electricity include lemon juice, vinegar, salt solution, sea water, and rain water. Non-conductors include milk, distilled water, and honey. - LEDs are better than light bulbs for testing liquid conductivity because LEDs glow with weak currents while bulbs may not heat up enough. - When passing current through a solution, the magnetic effect deflects a compass needle while the heating effect causes a bulb to glow.

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    This document contains 16 questions and answers about the chemical effects of electric current. Some key points covered include: - Liquids that are conductors of electricity include lemon juice, vinegar, salt solution, sea water, and rain water. Non-conductors include milk, distilled water, and honey. - LEDs are better than light bulbs for testing liquid conductivity because LEDs glow with weak currents while bulbs may not heat up enough. - When passing current through a solution, the magnetic effect deflects a compass needle while the heating effect causes a bulb to glow.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    61 views3 pages

    8th Chemical Effects of Electric Current Solved Questions

    Uploaded by

    Kavitha K
    This document contains 16 questions and answers about the chemical effects of electric current. Some key points covered include: - Liquids that are conductors of electricity include lemon juice, vinegar, salt solution, sea water, and rain water. Non-conductors include milk, distilled water, and honey. - LEDs are better than light bulbs for testing liquid conductivity because LEDs glow with weak currents while bulbs may not heat up enough. - When passing current through a solution, the magnetic effect deflects a compass needle while the heating effect causes a bulb to glow.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 3

    JSUNIL TUTORIAL ,SAMASTIPUR

    Q1. Which of the following liquids conduct electricity & which do not conduct
    electricity?

    Lemon juice, Milk, Vinegar, Salt solution, Distilled water, Honey, Sea water, Rain
    water.

    Ans: Conducting: Lemon juice, Vinegar, Salt solution, sea water, Rain water Non
    Conducting: Milk, Distilled water, Honey.

    Q2. What is advantage of using LED over bulb in testing the electrical
    conductivity of liquids?

    Ans: When electric current flows through a bulb then due to heating effect of current,
    the filament of the bulb gets heated up to a high temperature & it starts glowing. Now
    for a liquids having low electrical conductivity, the current flowing through the circuit is
    very weak due to which the filament does not get heated sufficiently & hence the bulb
    does not glow. Therefore LED is used in place of bulb because LED glows even
    when weak electric current flows in the circuit.

    Q3. Which effect of electric current is utilized for detecting the flow of current
    through a solution:

    a) When a torch bulb is used? b) When a magnetic compass is used?

    Ans: a) Heating effect b) Magnetic effect.

    Q4. Distilled water does not conduct electricity. What substances can be added
    to distilled water in small amounts to make it a good conductor of electricity?

    Ans: Salt, acid & base.

    Q5. In case of a fire, before the fireman uses the water hoses to throw water to
    douse fire, they shut off the electricity supply for the area. Explain why this is
    done?

    Ans: To prevent electrocution of fireman because ordinary water is conductor of


    electricity.

    Q6. When the free ends of a conductivity tester (made by using a battery
    connected to a wire wound around a compass) are dipped into a solution, the
    magnetic needle shows deflection. Can you give the reason of this deflection?

    CLASS VIII Chemical effects of electric current solved Questions Page 1


    JSUNIL TUTORIAL ,SAMASTIPUR

    Ans: Electric current flowing through the wire produces a magnetic field around it.
    And this magnetic field of electric current acts on the magnetic needle of compass &
    deflects it.

    Q7. What effects does an electric current produce when flowing through a
    conducting solution?

    Ans: When an electric current flows through the conducting solution, it causes a
    chemical reaction (or chemical change). These chemical reactions may produce
    following effects:

    i) Bubbles of gas/es may be formed on the electrodes.

    ii) Deposits of metals may form on electrodes.

    iii) Change in colour of solution may occur.

    Q8. When electric current is passed through acidified water then what is
    produced at

    a) Positive carbon electrode (anode)? b) Negative carbon electrode


    (cathode)?

    Ans: a) oxygen gas b) hydrogen gas.

    Q9. Which effect of electric current is utilized when a thin layer of chromium
    metal is deposited on an iron tap? What is this process known as?

    Ans: Chemical effect of current is utilized. The process is known as electroplating.

    Q10. What is meant by electroplating? What is the purpose of electroplating?

    Ans: The process of depositing a layer of any desired metal on another material, by
    means of electricity, is called electroplating. Electroplating is done

    i) for protection against corrosion (or rusting).

    ii) for decorative purposes.

    Q11. Which properties of chromium metal make it suitable for electroplating it


    on car bumpers, bath taps & bicycle hand bars, etc., made of iron?

    Ans It has shiny appearance. It does not corrode easily. It resists scratches.

    CLASS VIII Chemical effects of electric current solved Questions Page 2


    JSUNIL TUTORIAL ,SAMASTIPUR

    Q12. Which metal is electroplated on iron for making ‘cans’ used for storing
    food & Why?

    Ans: Tin. Tin metal has shiny appearance, it does not corrode & it is non poisonous.
    Tin is less reactive than iron. Due to tin plating over the surface of iron, the food does
    not come in contact with iron & is protected from getting spoilt.

    Q13. For electroplating copper on an iron object, which terminal of the


    battery is connected to the iron objects?
    Ans: Negative terminal of the battery

    Q14. In the process of purification of copper metal, a thin plate of pure copper
    & a thick rod of impure copper are used as electrodes & a metal salt solution is
    used as an electrolyte:

    a) Which electrode is connected to the positive terminal of the battery?

    b) Which electrode is connected to the negative terminal of the battery?

    c) Which metal salt solution is taken as electrolyte?

    Ans: a) Thick rod of impure copper. b) Thin rod of pure copper. c) Copper sulphate
    solution.

    Q15. Write down the important points which should be remembered while
    electroplating?

    Ans: i) The metal on which electroplating is to be done should be cathode i.e., the
    negative electrode.

    ii) The metal to be deposited should be anode i.e., the positive electrode.

    iii) A water soluble salt of the ‘metal to be deposited’ is taken as the electrolyte.

    Q16. On what factors the chemical effect produced by an electric current


    depends?

    Ans: The chemical effect produced by an electric current depends on the nature of
    conducting solution (through which it is passed), & on the nature of electrodes used
    for passing the electric current

    CLASS VIII Chemical effects of electric current solved Questions Page 3

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