Class 8 Practice – Level 2 – Set 2 – Chemical Effects of Electric Current

Total questions: 25

Why is gold used for electroplating in jewelry, even if it is expensive?

Gold can change the weight of jewelry

Gold is used because it does not corrode and is attractive

Gold can alter the jewelry's flexibility

Gold can easily dissolve in water

None

Which of the following is not a benefit of electroplating?

To make metals rust quickly

To improve the appearance of objects

To prevent corrosion

To make objects more durable

None

Why is the object being coated connected to the negative terminal during electroplating?

So that it can repel positive ions

To attract metal ions from the solution

To avoid reactions at the positive terminal

To ensure the electrolyte remains stable

None

What is the main purpose of electroplating in the production of kitchenware?

To add colors to the utensils

To make the utensils flexible

To create a protective layer that is safe and easy to clean

To make utensils heavier

None

What occurs at the anode during the electrolysis process?

Positive ions move towards the anode and are reduced

Negative ions move towards the anode and are oxidized

Both positive and negative ions move away from the anode

Ions lose their charge

None

Which process uses electrolysis for metal purification?

Alloy production

Electro-refining

Metal coating

Rusting prevention

None

When lead bromide is electrolyzed, which substance is produced at the anode?

Lead metal

Bromine gas

Oxygen gas

Chlorine gas

None

What factor can enhance the rate of electrolysis in a solution?

Lowering the temperature

Reducing the concentration of ions

Increasing the voltage

Using a larger anode

None

In the electrolysis of copper chloride, why does copper accumulate on the cathode?

The copper is neutralized in the solution

Copper ions repel each other

The positive electrode attracts all ions

Copper ions gain electrons at the cathode

None

10.

What does the production of a new substance during electrolysis indicate about the solution?

The solution has decomposed

The solution has evaporated

The solution is solidified

The solution is neutralized

None

11.

In which solution do ions move freely, facilitating a chemical reaction through electric current?

Pure distilled water

Saltwater solution

Alcohol solution

Sugar solution

None

12.

When testing lemon juice for conductivity, what will indicate that it conducts electricity?

The juice changes color

The juice loses its sour taste

The juice evaporates

An LED or bulb lights up

None

13.

Why does sugar solution fail to conduct electricity while saltwater does?

Sugar does not dissociate into ions

Sugar crystals are too large

Sugar does not dissociate into ions

Sugar reduces the temperature

None

14.

Why is an LED a suitable tool for testing weak electrical conductors?

It requires high current to glow

It only works with strong conductor

It glows even with low current

It is cheaper than a bulb

None

15.

If an LED does not light up while testing a liquid, what could this imply?

The liquid is a strong conductor

The LED is defective

The liquid is a poor conductor

The electrodes are too close

None

16.

What characteristic of hydrochloric acid enables it to conduct electricity in water?

It dissolves completely

It releases H⁺ ions

It forms large molecules

It evaporates quickly

None

17.

Why does pure acetic acid exhibit low conductivity compared to its aqueous solution?

Acetic acid is neutral

Water reduces its conductivity

Acetic acid does not ionize much on its own

Acetic acid is non-metallic

None

18.

What can be inferred about an unknown liquid if it turns blue litmus paper red?

It is a poor conductor

It is a conductor due to its acidic nature

It will be neutral

It will not conduct at all

None

19.

Which liquid is expected to conduct electricity effectively?

Vegetable oil

Vinegar

Pure alcohol

Distilled water

None

20.

Which solution would be a better conductor: baking soda or sugar solution, and why?

Sugar solution, because it dissolves fully

Baking soda solution, because it forms ions in water

Neither, as both are non-conductive

Both equally

None

21.

Which factor is crucial for successful electroplating on an object?

Using a solution that does not contain any metal

Keeping the object dry

Using a conducting solution with metal ions

Using high voltage only

None

22.

What happens to water during the electrolysis process?

It forms salt

It decomposes into hydrogen and oxygen gases

It forms metal deposits

It becomes acidic

None

23.

23. Why does copper deposit on the negative electrode in a solution of copper sulfate?

The copper is neutralized in the solution

Copper ions repel each other

Copper ions gain electrons at the cathode

The positive electrode attracts all ions

None

24.

24. If distilled water does not conduct electricity, what can be added to make it conductive?

Oil

Sand

Sugar

Salt

None

25.

When using an LED to test a solution, why might the LED not light up even if the solution conducts electricity weakly?

The current produced is too low for the LED to light

The LED is not connected properly

The solution conducts electricity very strongly

The LED only works with acidic solutions

None

1 out of 25

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Class 8 Practice – Level 2 – Set 2 – Chemical Effects of Electric Current

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