All Exams  >   Class 8  >   Science Class 8  >   All Questions

All questions of Chemical Effects of Electric Current for Class 8 Exam

 Electricity shows magnetic effect
  • a)
    True
  • b)
    False
Correct answer is option 'A'. Can you explain this answer?

C K Academy answered
 
If you run an electric current through a metal object, it exhibits magnetic behavior. However, simply passing current through iron doesn't make it magnetic. Yet, if you direct current through a coil wound around iron, it becomes magnetized. Even without iron in the coil, passing direct current through it generates a magnetic field akin to a magnet. Similarly, directing current through a coil around bismuth creates a magnet-like magnetic field.
 Electricity shows magnetic effect is true.

What type of water is a poor conductor of electricity?
  • a)
    Tap water
  • b)
    Well water
  • c)
    Distilled water
  • d)
    Pond water
Correct answer is option 'C'. Can you explain this answer?

BT Educators answered
Distilled water is a poor conductor of electricity because it lacks the dissolved salts and minerals that are present in natural water sources, which contribute to its conductivity.

Electroplating  is  based  on  the  heating  effect  of  electricity.
  • a)
    True
  • b)
    False
Correct answer is option 'B'. Can you explain this answer?

Ritu Joshi answered
The process of depositing a thin layer of a desired metal over a metal object with the help of electric current is called electroplating.
So, Electroplating is based on chemical effect of electricity.

Circuit is the closed path through which current flows.
  • a)
    True
  • b)
    False
Correct answer is option 'A'. Can you explain this answer?

Subset Academy answered
The correct option is A.
circuit A path through which electric charges flow. A continuous, unbroken path through which electrons can flow is a closed circuit. Charges, or current, can flow only through a closed circuit. A break or opening in a circuit creates an open circuit.

 Electric bulb glows due to chemical effect of electricity.
  • a)
    True
  • b)
    False
Correct answer is option 'B'. Can you explain this answer?

Amit Sharma answered
The electric bulb has a filament called tungsten when electricity passes through this filament, it heats up and glows. This heat is generated due to the passage of electric current and the drift of electrons due to the current and the resistance it causes.
Hence, the glowing of electric bulb is based on the heating effect of electric current.

Which of the following is added to make the copper sulphate solution more conducting?
  • a)
    Hydrochloric acid
  • b)
    Sulphuric acid
  • c)
    Nitric acid
  • d)
    Carbonic acid
Correct answer is option 'B'. Can you explain this answer?

Niharika Menon answered
Understanding Conductivity in Solutions
When discussing the conductivity of a solution, it’s essential to understand that conductivity depends on the presence of ions in the solution. More ions typically mean better conductivity.
Why Add Sulphuric Acid?
Sulphuric acid (H2SO4) is a strong acid that dissociates completely in water, providing a significant number of hydrogen ions (H+) and sulfate ions (SO4^2-). This increase in ion concentration enhances the solution's ability to conduct electricity.
Comparison with Other Acids
- Hydrochloric Acid (HCl): While HCl is also a strong acid and would increase conductivity, it does not provide additional sulfate ions, which can further enhance the solution's properties.
- Nitric Acid (HNO3): Similar to HCl, nitric acid is a strong acid, but it introduces nitrate ions (NO3-) instead of sulfate ions, which may not be as effective in this specific context.
- Carbonic Acid (H2CO3): This is a weak acid that does not dissociate completely in solution, leading to fewer ions and, consequently, lower conductivity compared to strong acids.
Conclusion
Thus, the correct answer is option 'B' (Sulphuric acid), as it significantly increases the number of ions in the copper sulphate solution, enhancing its conductivity. This makes sulphuric acid the best choice among the options provided.

In the activity where you take 250 mL of distilled water in a beaker, dissolve two teaspoonfuls of copper sulphate, add dilute sulphuric acid, clean two copper plates, connect them to a battery, and immerse them in the solution, what happens to the copper plate connected to the negative terminal after passing current?
  • a)
    It dissolves into the solution.
  • b)
    It remains unchanged.
  • c)
    Copper gets deposited on it.
  • d)
    It turns into sulphate.
Correct answer is option 'C'. Can you explain this answer?

Ashutosh Iyer answered
Understanding the Electrolysis Process
In the described activity, you are performing an electrolysis experiment using copper sulphate solution. When current is passed through the solution with copper plates, specific chemical reactions occur.
Role of Electrodes
- The two electrodes (copper plates) are connected to a battery.
- The plate connected to the negative terminal acts as the cathode, while the one connected to the positive terminal is the anode.
What Happens at the Cathode?
- When current flows, copper ions (Cu²⁺) from the copper sulphate solution migrate towards the cathode (negative plate).
- At the cathode, a reduction reaction occurs where Cu²⁺ ions gain electrons and are converted into solid copper.
Result of the Reaction
- This process leads to the deposition of copper metal on the negative plate.
- Therefore, as time passes, you will observe that the cathode plate becomes thicker due to the accumulation of copper.
Conclusion
- The correct answer is option 'C': Copper gets deposited on it.
- This phenomenon illustrates the principles of electrolysis and the behavior of ions in an electrolyte solution when exposed to an electric current.

In battery two or more cells are connected in
  • a)
    Series 
  • b)
    Random
  • c)
    Positive and Negative terminals 
  • d)
    Parallel
Correct answer is option 'A'. Can you explain this answer?

Gitanjali Kaur answered
2 or 3 cells are combined and connected electrically in series and have two main terminals: positive and negative terminals. 

 Flow of electrons is called
  • a)
    Electroplating
  • b)
    Electric current
  • c)
    Electrodes
  • d)
    Electrolyte.
Correct answer is option 'B'. Can you explain this answer?

Shubham Sharma answered
Electricity is a term used to describe the energy produced (usually to perform work) when electrons are caused to directional (not randomly) flow from atom to atom. In fact, the day-to-day products that we all benefit from, rely on the movement of electrons. This movement of electrons between atoms is called electrical current. 

In LEDs, the longer lead (wire) is always connected to the _______ terminal
  • a)
    negative
  • b)
    neutral
  • c)
    positive
  • d)
    Any terminal
Correct answer is option 'C'. Can you explain this answer?

Understanding LED Leads
LEDs (Light Emitting Diodes) are semiconductor devices that emit light when an electric current passes through them. They have two leads, which connect to different terminals in a circuit.
Lead Length Significance
- The longer lead of an LED is known as the anode.
- The anode is always connected to the positive terminal of the power supply.
Why the Longer Lead is Positive
- Polarity in LEDs: LEDs are polarized components, meaning they must be connected to a power source in a specific way for them to function correctly. Connecting them incorrectly can damage the LED or prevent it from lighting up.
- Current Flow Direction: Current flows from the positive terminal (anode) to the negative terminal (cathode). The longer lead being the anode ensures that the current can flow into the LED correctly, allowing it to emit light.
Identifying LED Leads
- Long Lead: Connects to the positive terminal.
- Short Lead: This is the cathode, which connects to the negative terminal.
Conclusion
Understanding the polarity of LEDs is crucial for their proper operation. By ensuring the longer lead is connected to the positive terminal, users can enjoy the full functionality of their LED devices, whether in simple circuits or more complex applications.

Which metal is electroplated on iron for making “cans” for storing food and drinks?
  • a)
    Chromium metal
  • b)
    Silver metal
  • c)
    Tin metal
  • d)
    Copper metal
Correct answer is option 'C'. Can you explain this answer?

Baishali Datta answered
There are several metals that can be electroplated onto iron to improve its properties or appearance. Some common metals used for electroplating on iron include:

1. Nickel: Electroplating iron with nickel provides a protective layer that enhances corrosion resistance, hardness, and durability. It also offers a bright and attractive finish.

2. Chromium: Chromium electroplating on iron forms a thin layer of chrome, which not only enhances corrosion resistance but also provides a shiny, reflective surface. It is often used in decorative applications.

3. Zinc: Electroplating iron with zinc, known as galvanizing, is commonly used to prevent rust and corrosion. It provides a sacrificial layer that corrodes before the iron, protecting it from environmental exposure.

4. Copper: Copper electroplating on iron can improve electrical conductivity and thermal conductivity. It is also used for decorative purposes due to its reddish-brown color.

5. Silver: Silver plating on iron is occasionally used for its antimicrobial properties, as silver possesses natural germicidal effects. It is commonly used in the food and medical industries.

These are just a few examples, and other metals like gold, tin, brass, and bronze can also be electroplated onto iron for specific purposes.

An electrolyte is:
  • a)
    a metal
  • b)
    a solution
  • c)
    a liquid that conducts current
  • d)
    all of above.
Correct answer is option 'C'. Can you explain this answer?

Jaideep Nair answered
An electrolyte is:

An electrolyte is a substance that conducts electricity when dissolved in water or melted. It is essential for various biological processes and is also used in many industrial applications.

Explanation:

1. Definition:
An electrolyte is a substance that contains free ions and can conduct electric current. It can be in the form of a solid, liquid, or solution. When an electrolyte dissolves in water or melts, its ions become mobile and are able to carry electric charge.

2. Conductivity of Electrolytes:
Electrolytes conduct electric current because they contain ions that are free to move. When a potential difference is applied across an electrolyte, the positive ions move towards the negative electrode (cathode) and the negative ions move towards the positive electrode (anode). This movement of ions constitutes the flow of electric current.

3. Types of Electrolytes:
There are two types of electrolytes:

- Strong Electrolytes: These electrolytes completely dissociate into ions when dissolved in water or melted. Examples include sodium chloride (NaCl), potassium hydroxide (KOH), and sulfuric acid (H2SO4).

- Weak Electrolytes: These electrolytes only partially dissociate into ions when dissolved in water or melted. Examples include acetic acid (CH3COOH) and ammonia (NH3).

4. Applications of Electrolytes:
Electrolytes have numerous applications in various fields, some of which include:

- Batteries: Electrolytes are used in batteries to facilitate the flow of ions between the electrodes and generate electrical energy.

- Electroplating: Electrolytes are used in electroplating processes to deposit a layer of metal onto a surface.

- Electrolysis: Electrolytes are used in electrolysis processes to separate compounds into their constituent elements.

- Medical Applications: Electrolytes are essential for the proper functioning of the human body. They help maintain fluid balance, nerve function, and muscle contraction.

Conclusion:
An electrolyte is a substance that conducts electric current when dissolved in water or melted. It is essential for various biological processes and has numerous industrial applications. Understanding the properties and behavior of electrolytes is crucial in various scientific and industrial fields.

Which of the following is a poor conductor of electricity?
  • a)
    Steel spoon
  • b)
    Iron nail
  • c)
    Air
  • d)
    Tap water
Correct answer is option 'C'. Can you explain this answer?

Rishika Dey answered
Tap water, iron nail and steel spoon are good conductor of electricity but air is poor conductor of electricity.

Why are LEDs extensively used to replace bulbs?
(i) Consume less electricity
(ii) Have longer life
(iii) Have more power
  • a)
    (i),(ii) and (iii)
  • b)
    Only (ii) and (iii)
  • c)
    Only (i) and (iii)
  • d)
    (i) and (ii)
Correct answer is option 'D'. Can you explain this answer?

LEDs are extensively used to replace bulbs because they consume less electricity and have a longer life. They do not necessarily have more power; rather, they are known for being more energy-efficient, which makes them a popular choice for lighting.

Distilled water is
  • a)
    Poor conductor
  • b)
    Good conductor
  • c)
    Both (a) and (b)
  • d)
    None.
Correct answer is option 'A'. Can you explain this answer?

Shubham Sharma answered
Distilled water is a poor conductor  of electricity because it doesn't contain any dissolved salts in it which can provide it ions to conduct electricity.

What should be checked first if the bulb in the tester does not glow when the circuit is completed?
  • a)
    The type of liquid being tested
  • b)
    The tightness of all connections
  • c)
    The length of the wires
  • d)
    The material of the tester leads
Correct answer is option 'B'. Can you explain this answer?

Upsc Toppers answered
If the bulb does not glow when the circuit is completed, the first thing to check is the tightness of all connections. Loose connections can prevent the circuit from being completed, causing the bulb to not glow.

Why is it advised not to handle electrical appliances with wet hands or while standing on a wet floor?
  • a)
    Wet conditions increase air conductivity
  • b)
    Wet conditions prevent electric current flow
  • c)
    Water is a good conductor of electricity
  • d)
    Water reduces appliance efficiency
Correct answer is option 'C'. Can you explain this answer?

Understanding Electrical Safety
Handling electrical appliances with wet hands or while standing on a wet floor poses significant risks due to the properties of water and its interaction with electricity. Here’s a detailed explanation:
Why Water is Dangerous
- Water as a Conductor: Water, especially when it contains impurities (like minerals and salts), is a good conductor of electricity. This means that when your hands are wet, they can easily transmit electric current from an appliance to your body.
- Increased Risk of Electric Shock: If you touch an electrical appliance with wet hands, the moisture can create a pathway for the electric current to flow through your body. This may lead to electric shock, which can cause serious injury or even be fatal.
Impact of Wet Floors
- Ground Conductivity: Standing on a wet floor also increases the risk of electric shock. Wet surfaces can conduct electricity, which means that if an appliance malfunctions or has a fault, the current could easily travel through the water on the floor and reach you.
- Loss of Control: Wet conditions can make it difficult to maintain grip and balance, increasing the likelihood of accidents or falls when handling electrical devices.
Precautions to Take
- Avoid Wet Conditions: Always ensure your hands and the surrounding area are dry before using electrical appliances.
- Use Insulated Equipment: Whenever possible, use appliances designed for wet conditions, which have safety features to reduce the risk of electric shock.
In summary, handling electrical appliances with wet hands or on wet surfaces is dangerous due to the conductive nature of water, significantly increasing the risk of electric shock. Always prioritize safety to prevent accidents.

Which of the following liquid is good conductor of electricity?
  • a)
    Sugar solution
  • b)
    Alcohol
  • c)
    Distilled water
  • d)
    Sea water
Correct answer is 'D'. Can you explain this answer?

Sanjana Bose answered
Sea water is a better conductor because it has dissolved and dissociated ions.
The conductivity of water depends on the concentration of dissolved ions in solution.
The units of conductivity are Siemens per metre S/m.
Deionised water by its nature has very few ions. Its conductivity is about 
5.5
μ
S/m.
Sea water has a relatively large number of Sodium and Chloride ions and has a conductivity of around 5S/m. This is because the Sodium Chloride salt dissociates into ions.
Hence, sea water is about a million times more conductive than fresh water.

How can we detect a weak current using a tester?
  • a)
    Use a thicker wire
  • b)
    Use a LED instead of a bulb
  • c)
    Increase the battery voltage
  • d)
    Use a larger compass needle
Correct answer is option 'B'. Can you explain this answer?

Understanding the Use of LED in Detecting Weak Currents
When it comes to detecting weak currents, the choice of the indicator plays a crucial role. Using an LED instead of a traditional bulb is an effective method for several reasons.
Why Choose LED?
- Lower Power Requirement:
- LEDs require much less current to illuminate compared to incandescent bulbs. This makes them sensitive to low current levels, allowing them to light up even with weak currents.
- Higher Sensitivity:
- Due to their design, LEDs can respond to lower voltage and current. They effectively indicate the presence of a current that might not be sufficient to activate a conventional bulb.
Drawbacks of Other Options:
- Thicker Wire:
- Using thicker wire does not enhance the ability to detect weak currents; it merely reduces resistance for stronger currents.
- Increased Battery Voltage:
- Raising the voltage could potentially damage sensitive components, including LEDs, and does not address the detection of weak currents.
- Larger Compass Needle:
- While a larger compass needle can indicate magnetic fields, it is not designed for direct current measurement and may not provide clear visibility of weak current levels.
Conclusion
Using an LED as a current tester is advantageous due to its efficiency and sensitivity in low current scenarios. This makes it an ideal choice for detecting weak currents in various applications.

An electric lamp glows due to
  • a)
    Chemical effect
  • b)
    Magnetic effect
  • c)
    Heating effect
  • d)
    None.
Correct answer is option 'C'. Can you explain this answer?

Amita Verma answered
When electric current passes through a bulb, the filament of the bulb heats up to a high temperature. This is called heating effect of current. The temperature is so high that it starts glowing. 

However, if the current through a circuit is weak, the filament does not get heated up sufficiently and it does not glow. 

Electroplating is based on:
  • a)
    magnetic effect of electricity
  • b)
    chemical effect of electricity
  • c)
    heating effect of electricity
  • d)
    physical effect of electricity.
Correct answer is option 'B'. Can you explain this answer?

Explanation:
Electroplating is a process of depositing a thin layer of metal on an object by using electricity. It is based on the chemical effect of electricity. The process involves the following steps:

1. Preparation of the object: The object to be plated is first cleaned and polished to remove any impurities or dirt.

2. Preparation of the electrolyte: An electrolyte is a solution of a salt of the metal to be deposited. It is prepared by dissolving the salt in water.

3. Setting up the electroplating cell: The electroplating cell consists of the object to be plated, the electrolyte solution, and a source of direct current (DC) electricity. The object to be plated is connected to the negative terminal of the DC power source, while the metal to be deposited is connected to the positive terminal.

4. Plating process: When the DC current is passed through the electrolyte solution, the metal ions in the solution are attracted to the object to be plated. These metal ions then react with the object's surface, forming a thin layer of metal on it.

5. Finishing: Once the plating process is complete, the object is removed from the electrolyte solution and washed to remove any excess electrolyte or impurities.

Conclusion:
The chemical effect of electricity is what makes electroplating possible. It involves the use of an electrolyte solution, a source of direct current (DC) electricity, and the attraction of metal ions to the object to be plated. The result is a thin layer of metal deposited on the object, which can improve its appearance, durability, and resistance to corrosion.

Which of the following gas is formed at the electrode connected to the negative terminal of the battery?
  • a)
    Nitrogen gas
  • b)
    Hydrogen gas
  • c)
    Oxygen gas
  • d)
    Carbon dioxide gas
Correct answer is option 'B'. Can you explain this answer?

Pallabi Gupta answered
Understanding the Electrolysis Process
In electrolysis, an electric current is passed through a solution or molten substance, causing it to decompose into its constituent elements. The electrodes play a crucial role in this process.
Electrodes and Their Functions
- Anode: The positive electrode where oxidation occurs.
- Cathode: The negative electrode where reduction occurs.
Gas Formation at the Cathode
When a battery is connected to an electrolyte solution, during electrolysis:
- At the Cathode: Reduction takes place. If the electrolyte is a solution of water or an acid, hydrogen ions (H+) from the solution gain electrons and are reduced to form hydrogen gas (H2).
- Chemical Reaction: The reaction at the cathode can be simplified as:
- 2H+ + 2e- → H2 (gas)
Why Hydrogen Gas is Formed
- Electrolyte Type: In most common electrolytes (like water with a small amount of acid), hydrogen ions are readily available.
- Electrode Reaction: The cathode attracts positive ions, leading to the production of hydrogen gas through the reduction of hydrogen ions.
Conclusion
Thus, when a battery powers the electrolysis process, the gas formed at the electrode connected to the negative terminal (cathode) is indeed hydrogen gas (option B).

Why are tin cans used for storing food made by electroplating tin onto iron?
  • a)
    Tin is stronger than iron
  • b)
    Tin is less reactive than iron
  • c)
    Tin is cheaper than iron
  • d)
    Tin is a better conductor than iron
Correct answer is option 'B'. Can you explain this answer?

Simran Datta answered
Why Use Tin for Food Storage Cans?
Tin cans are a common choice for food storage due to their protective properties. The process of electroplating tin onto iron serves specific purposes that enhance the longevity and safety of canned foods.
Less Reactivity of Tin
- Corrosion Resistance: Tin is significantly less reactive than iron. This characteristic helps prevent the can from rusting and reacting with acidic foods, which could compromise food safety and flavor.
- Food Safety: By using tin, the likelihood of harmful reactions between the can material and the food is minimized. This is particularly important for preserving the nutritional quality of the food.
Strength and Durability
- Structural Integrity: While iron provides strength to the can, tin acts as a barrier. The combination allows for a durable container that withstands handling and storage conditions.
Cost Considerations
- Cost-Effectiveness: Although tin may not be cheaper than iron, its use in small amounts as a coating allows manufacturers to keep costs down while providing a safe storage solution.
Conclusion
In summary, the choice of tin electroplated onto iron for food storage cans is primarily due to the lower reactivity of tin. This ensures that the food remains safe, fresh, and free from undesirable reactions, making it an optimal choice for food preservation.

What does the presence of mineral salts in natural water contribute to?
  • a)
    Increased viscosity
  • b)
    Good conductivity
  • c)
    Decreased temperature
  • d)
    Lowered pH
Correct answer is option 'B'. Can you explain this answer?

Varun Sharma answered
Understanding Mineral Salts in Natural Water
The presence of mineral salts in natural water significantly influences its properties, particularly conductivity.
1. What are Mineral Salts?
- Mineral salts are inorganic compounds that dissolve in water to form ions.
- Common examples include sodium, potassium, calcium, magnesium, chloride, sulfate, and bicarbonate.
2. Contribution to Conductivity
- Conductivity refers to the ability of water to conduct electric current.
- When mineral salts dissolve in water, they dissociate into positively and negatively charged ions.
3. Mechanism of Conductivity
- The free movement of these ions allows the water to carry electric current effectively.
- Higher concentrations of dissolved salts result in increased ion availability, thus enhancing conductivity.
4. Comparison with Other Options
- Increased Viscosity (Option A): Mineral salts generally do not increase viscosity; in fact, they can lead to a slight decrease in viscosity due to the presence of ions.
- Decreased Temperature (Option C): The presence of mineral salts does not inherently decrease temperature; in some cases, it may slightly increase it due to exothermic dissolution processes.
- Lowered pH (Option D): While certain mineral salts can affect pH, not all salts lower pH. The overall impact on pH depends on the specific ions present.
5. Conclusion
- The primary contribution of mineral salts in natural water is to enhance its conductivity, making option 'B' the correct answer. This conductivity is essential for various ecological processes and the overall health of aquatic environments.

When salt is dissolved in distilled water, it does not conduct electricity.
  • a)
    True
  • b)
    False
Correct answer is option 'B'. Can you explain this answer?

Niti Singh answered
False. When salt is dissolved in distilled water, it creates an electrolyte solution and does conduct electricity. The ions in the salt dissolve in water and become mobile, allowing the solution to conduct electricity.

In the activity where you collect small plastic or rubber caps of discarded bottles, pour one teaspoon of lemon juice or vinegar into one cap, and dip the ends of a tester with a bulb into the liquid, what is observed if the liquid is a good conductor?
  • a)
    The bulb does not glow at all.
  • b)
    The bulb glows brightly.
  • c)
    The bulb flickers intermittently.
  • d)
    The bulb glows dimly.
Correct answer is option 'B'. Can you explain this answer?

Understanding Conductivity in Liquids
When testing the conductivity of liquids like lemon juice or vinegar using a simple circuit with a tester and a bulb, the key concept is the presence of ions in the liquid.
What is Electrical Conductivity?
- Electrical conductivity refers to the ability of a substance to allow the flow of electric current through it.
- Liquids that contain ions (charged particles) can conduct electricity well.
Lemon Juice and Vinegar as Conductors
- Lemon juice and vinegar are acidic solutions, which means they contain a significant amount of ions (H+ ions).
- These ions facilitate the movement of electric charge, allowing current to flow.
Process of the Experiment
- When you pour lemon juice or vinegar into the cap and dip the tester's bulb into the liquid, you are completing a circuit.
- If the liquid is a good conductor, it allows electricity to flow through it.
Why the Bulb Glows Brightly
- In this scenario, the bulb glows brightly because the electric current is flowing freely through the lemon juice or vinegar.
- The high concentration of ions means that there is little resistance to the flow of electricity, resulting in a bright glow.
Conclusion
- Therefore, when the liquid is a good conductor like lemon juice or vinegar, the bulb will glow brightly, indicating effective conductivity.
- This experiment illustrates the principle of how certain liquids can conduct electricity based on their ionic content.

When electrodes are immersed in water and electricity is passed, the bubbles formed on the positive terminal is actually _______ gas.
  • a)
    Hydrogen
  • b)
    Carbon dioxide
  • c)
    Oxygen
  • d)
    Nitrogen
Correct answer is option 'C'. Can you explain this answer?

When electrodes are immersed in water and electricity is passed through it, water undergoes electrolysis. The water molecules are split into hydrogen and oxygen gases. The hydrogen gas is released at the negative terminal (cathode), and the oxygen gas is released at the positive terminal (anode). Therefore, the bubbles formed on the positive terminal are oxygen gas.

Adding common salt to distilled water makes it:
  • a)
    good conductor
  • b)
    insulator
  • c)
    none
  • d)
    both  (a) and (b)
Correct answer is option 'A'. Can you explain this answer?

EduRev Class 8 answered
Adding common salt to distilled water increases its conductivity.
When salt (sodium chloride) dissolves in water, it breaks down into sodium and chloride ions. This process enhances the solution's ability to conduct electricity. Here are some key points:
  • Salt Dissolves: Sodium chloride dissociates into ions.
  • Ion Movement: Ions carry electric charge through the solution.
  • Improved Conductivity: The presence of ions makes the solution a good conductor.
In contrast, distilled water on its own is a weak conductor of electricity due to the absence of dissolved ions. Therefore, adding common salt transforms distilled water into a solution that conducts electricity effectively.

Distilled water also conducts the electric current.
  • a)
    True
  • b)
    False
Correct answer is option 'B'. Can you explain this answer?

Ashwin Jain answered
Distilled water which is a pure form of water, is neither acidic nor basic in nature. So distilled water does not dissociate into ions. Since, conduction of electricity requires free ions so, distilled water does not conduct electricity.

Chapter doubts & questions for Chemical Effects of Electric Current - Science Class 8 2026 is part of Class 8 exam preparation. The chapters have been prepared according to the Class 8 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Class 8 2026 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

Chapter doubts & questions of Chemical Effects of Electric Current - Science Class 8 in English & Hindi are available as part of Class 8 exam. Download more important topics, notes, lectures and mock test series for Class 8 Exam by signing up for free.

Science Class 8

136 videos|531 docs|57 tests

Top Courses Class 8