Test: Fire: Friend and Foe- 2 - Class 7 MCQ

Fire can be:
- a good servant: Fire can be a useful tool in many ways. It provides heat and light, which are essential for cooking, heating, and other everyday activities. It can also be used to generate energy and power.
- created: Fire is created by combining fuel, heat, and oxygen. It is a chemical reaction known as combustion. Fuel can be anything that is flammable, such as wood, paper, or gas. Heat can be generated through a spark, friction, or other sources. Oxygen is necessary for the fire to sustain itself.
- a bad master: Fire can be destructive and dangerous when it is not controlled or contained. Uncontrolled fires can cause property damage, injuries, and even loss of life. They can spread quickly and be difficult to extinguish, especially in large-scale incidents like wildfires.
- both (a) and (c): Fire can serve as a good servant when used responsibly and for beneficial purposes. However, it can also become a bad master when it gets out of control or is misused.
Overall, fire is a powerful force that can have both positive and negative impacts. It is important to understand its properties and potential dangers to ensure its safe and responsible use.

Flash point or kindling temperature
- The temperature at which a fuel begins to burn is called the flash point or kindling temperature.
- It is the lowest temperature at which the vapors of a fuel can ignite when exposed to an open flame or spark.
- Once the fuel reaches its flash point, it releases enough vapors to form an ignitable mixture with air.
- At this temperature, a small ignition source can cause the fuel to ignite and sustain combustion.
- The flash point is an important characteristic of a fuel as it determines its fire hazard and safety precautions that need to be taken during storage, handling, and transportation.
- Different fuels have different flash points, depending on their chemical composition and physical properties.
- It is crucial to know the flash point of a fuel to ensure proper safety measures are in place to prevent accidents and fires.
Flash temperature
- Flash temperature is not the correct term for the temperature at which a fuel begins to burn.
- The flash temperature refers to the temperature at which a liquid fuel gives off enough vapor to form a flammable mixture above its surface, but not necessarily ignite.
- It is a measure of the volatility of the fuel and is important for determining its potential for flammability.
Fuel temperature
- Fuel temperature is a general term that refers to the temperature of the fuel itself.
- It does not specifically indicate the temperature at which the fuel begins to burn.
- The fuel temperature can vary depending on factors such as ambient temperature, storage conditions, and the heating or cooling of the fuel.
None of these
- The correct answer is not "None of these" as the flash point or kindling temperature is the specific term used to describe the temperature at which a fuel begins to burn.

Fire brigade is a band of fire-fighters

Fire is called a bad master because:
- Dangerous when not controlled: If fire is not kept under control, it can be extremely dangerous and destructive to everything in its path. Uncontrolled fires can cause widespread damage and even lead to loss of life.
- Causes harm and destruction: Fire has the potential to cause significant harm and destruction to both living beings and the environment. It can burn down homes, forests, and infrastructure, resulting in the loss of property and livelihoods.
- Difficult to extinguish: Once a fire starts, it can be challenging to extinguish, especially if it spreads rapidly or is fueled by highly flammable materials. This difficulty in controlling and extinguishing fires further emphasizes the need to treat fire with caution.
- Potential for injury and death: Fire poses a serious risk of injury or death to individuals in its vicinity. It can cause severe burns, smoke inhalation, and other life-threatening injuries. In hazardous situations, such as building fires, people may become trapped or unable to escape, leading to fatalities.
- Loss of resources: Fires can result in the loss of valuable resources, including natural habitats, crops, and livestock. This loss can have long-lasting impacts on ecosystems and the economy.
- Environmental impact: Uncontrolled fires release a significant amount of smoke, ash, and harmful gases into the atmosphere. This can lead to air pollution and contribute to climate change.
- Disruption of daily life: When fire occurs, it often leads to the evacuation of affected areas and disrupts the normal functioning of communities. People may lose their homes, belongings, and sense of security, leading to emotional distress and hardship.
Therefore, fire is called a bad master because it has the potential to cause harm, destruction, and loss if not properly controlled and managed.

Fuels available in natural form:
There are several fuels available in natural form that are commonly used for various purposes. These fuels include:
1. Cooking gas: Also known as liquefied petroleum gas (LPG), cooking gas is a popular fuel used for cooking in households. It is a byproduct of natural gas processing and oil refining.
2. Electricity: Although electricity is not a fuel in itself, it is generated from various sources such as fossil fuels, including coal and natural gas, as well as renewable sources like wind, solar, and hydro power.
3. Petrol: Petrol, also referred to as gasoline, is a commonly used fuel for transportation, especially in automobiles. It is derived from crude oil through a refining process.
4. Coal: Coal is a fossil fuel that is primarily used for electricity generation and industrial processes. It is formed from the remains of prehistoric plants that were buried and subjected to heat and pressure over millions of years.
These natural fuels play a significant role in meeting our energy needs and are widely used in various sectors of the economy. They are essential for cooking, transportation, electricity generation, and industrial processes. However, it is important to note that the use of some of these fuels, such as coal and petrol, contributes to environmental pollution and greenhouse gas emissions. Therefore, there is a growing emphasis on transitioning to cleaner and renewable sources of energy to mitigate the impact of fossil fuel consumption on the environment.

To determine the number of ways a fire can be put out, we need to consider the different methods or actions that can be taken to extinguish the fire.
Here are the different ways a fire can be put out:
1. Water:
- Using water to douse the flames is one of the most common methods of extinguishing a fire. This involves spraying water directly onto the fire or using a fire hose to flood the area.
2. Fire Extinguisher:
- Fire extinguishers are devices specifically designed to put out fires. There are different types of fire extinguishers, such as those that use foam, carbon dioxide, dry powder, or water mist, depending on the type of fire.
3. Fire Blanket:
- A fire blanket is a specially designed cloth that can be used to smother small fires. It is made of fire-resistant materials and can be draped over the flames to cut off the oxygen supply and extinguish the fire.
4. Sand or Dirt:
- In some cases, sand or dirt can be used to smother small fires. This method works by covering the flames with a thick layer of sand or dirt, which cuts off the oxygen supply and suffocates the fire.
5. Chemical Agents:
- Some fires may require the use of specific chemical agents to extinguish them. These agents can include foam, dry chemical powders, or specialized chemicals designed for specific types of fires, such as oil or electrical fires.
Based on the above methods, we can conclude that there are three ways a fire can be put out: water, fire extinguisher, and fire blanket. Therefore, the correct answer is option C: Three.

Fire is both a friend and a foe, depending on the circumstances and how it is used. Let's examine the reasons for each viewpoint.
Fire as a Friend:
- Heat and Light Source: Fire provides warmth and light, which are essential for survival, especially in colder environments or during the night.
- Cooking and Food Preparation: Fire is used for cooking food, making it safe to consume by killing bacteria and parasites. It also enhances the taste and texture of food.
- Purification: Fire can be used to purify water by boiling it, making it safe to drink.
- Energy Source: Fire has been historically used as a source of energy, powering engines and machinery.
- Cultural Significance: Fire is often associated with celebrations, rituals, and gatherings, bringing people together and fostering a sense of community.
Fire as a Foe:
- Destruction: Uncontrolled or accidental fires can cause immense damage to property, forests, and wildlife. They can lead to the loss of homes, businesses, and even lives.
- Environmental Impact: Large-scale fires release harmful gases and pollutants into the atmosphere, contributing to air pollution and climate change.
- Health Hazards: Fire produces smoke and toxic fumes, which can be harmful to human health, causing respiratory problems and other illnesses.
- Accidents and Injuries: Fire accidents can result in severe burns, injuries, and fatalities.
- Wildfires: Natural wildfires can spread rapidly, destroying ecosystems, displacing wildlife, and endangering human lives.
Conclusion:
Fire is a powerful force that can be both beneficial and destructive. It is essential to use fire responsibly and take necessary precautions to minimize its negative impacts. Understanding the potential risks and benefits of fire allows us to harness its power effectively and ensure our safety and well-being.

Carbon dioxide:

• Carbon dioxide is commonly used to extinguish small fires.


• It works by displacing oxygen, which is necessary for combustion, and thus suffocating the fire.


• When carbon dioxide is released onto a fire, it forms a blanket of gas that prevents oxygen from reaching the fuel source, thereby extinguishing the flames.


• Carbon dioxide is typically stored in high-pressure cylinders and can be discharged using specialized fire extinguishers.

Oxygen:

• Oxygen is not used to extinguish fires.


• Oxygen supports combustion and can actually make a fire burn more intensely.


• Introducing oxygen to a fire can cause it to spread or reignite.

Nitrogen:

• Nitrogen is also not typically used to extinguish fires.


• While nitrogen is an inert gas and does not support combustion, it is not as effective as carbon dioxide in displacing oxygen and suffocating a fire.


• Carbon dioxide is generally preferred over nitrogen for fire suppression.

None of these:

• This option is incorrect as carbon dioxide is indeed used to extinguish fires.


• Therefore, the correct answer is option C: Carbon dioxide.

In summary, carbon dioxide is commonly used to extinguish small fires as it displaces oxygen and suffocates the fire. Oxygen and nitrogen are not used for fire extinguishment as oxygen supports combustion and nitrogen is not as effective as carbon dioxide in suffocating a fire.

Fire is a bad master if it is:
Made by coal:
- Coal fires can release harmful gases and pollutants into the air, leading to air pollution and respiratory issues.
- Coal fires can also cause environmental damage, such as deforestation and habitat destruction during the mining process.
Made by electricity:
- Electrical fires can be dangerous and destructive, causing property damage and potential loss of life.
- Electrical fires can be difficult to control and extinguish, leading to further damage if not properly addressed.
Under:
- Fires that occur underground, such as in coal mines or oil wells, can be extremely hazardous.
- Underground fires are difficult to reach and extinguish, often leading to prolonged burning and environmental damage.
Uncontrolled:
- Uncontrolled fires can quickly spread and cause widespread destruction.
- Uncontrolled fires can endanger lives, destroy property, and have severe environmental consequences.
- Uncontrolled fires can also disrupt communities, economies, and ecosystems.
In conclusion, fire is a bad master when it is made by coal, made by electricity, occurs under the ground, or is uncontrolled. These situations can lead to harmful effects on the environment, health, and safety. It is important to properly manage and control fires to prevent their negative consequences.

How to put out a fire:
To put out a fire, it is important to remove either the fuel or the oxygen that is sustaining the fire. This can be achieved by following these steps:
1. Eliminate the fuel:
- Identify the source of the fuel that is feeding the fire.
- Remove any flammable materials that are in close proximity to the fire.
- Cut off the supply of fuel by turning off gas or electricity sources, if applicable.
- Use a fire extinguisher to spray a fire retardant substance on the fuel source, effectively smothering the fire.
2. Remove the oxygen:
- Close any doors or windows in the area to limit the oxygen supply.
- Cover the fire with a fire blanket or a thick, non-flammable material to cut off the oxygen flow.
- Use a fire extinguisher that contains carbon dioxide or another oxygen-displacing agent to suffocate the fire.
3. Call for help:
- Even if you are able to successfully put out the fire, it is important to contact emergency services to ensure that the situation is under control.
Remember, it is crucial to prioritize your safety when attempting to put out a fire. If the fire becomes uncontrollable or poses a threat to your well-being, evacuate the area immediately and wait for professional assistance.

Early man might have experienced fire by:
- Watching lightning and volcanoes: Early man would have observed natural phenomena such as lightning strikes and volcanic eruptions, which involve the presence of fire. They might have observed the destructive power and heat generated by these natural events, leading to the curiosity to harness fire for their own use.
- Watching fireflies: Fireflies, also known as lightning bugs, emit a natural form of light due to a chemical reaction in their bodies. Early man might have observed these glowing insects and realized the potential of fire as a source of light and heat.
- Keeping it under wraps: Early man might have accidentally discovered fire through natural causes, such as wildfires or lightning strikes, and then learned to control and maintain it. They might have used various methods to keep fire burning, such as keeping it covered with leaves or in a cave, allowing them to benefit from its warmth, light, and cooking properties.
- None of these: It is also possible that early man discovered fire through a different means altogether, which is not mentioned in the given options. This could include other natural events or experimental attempts to create fire.
In conclusion, while the exact method through which early man experienced fire may not be definitively known, it is likely that they observed natural occurrences of fire, such as lightning and volcanic eruptions, or even the behavior of fireflies. Over time, they learned to control and maintain fire, leading to its use in various aspects of their daily lives.

To stop oxygen from reaching the burning material, we can use a damp blanket or a sack. Here's a detailed explanation:
1. Water:
- Water is an effective agent to extinguish fires. However, it may not be suitable for all types of fires.
- Water can be used to cool down the burning material and reduce the temperature below its ignition point, which helps to stop the fire.
- It also helps to reduce the amount of oxygen available for combustion.
2. Damp blanket or a sack:
- A damp blanket or a sack can be used to smother the fire by cutting off the supply of oxygen.
- By covering the burning material with a damp blanket or a sack, the oxygen supply is limited, and the fire is suffocated.
- The dampness of the blanket or sack also helps to reduce the temperature and prevent the fire from spreading further.
3. Carbon:
- Carbon dioxide (CO2) is commonly used as a fire extinguishing agent in fire extinguishers.
- When CO2 is released, it displaces the oxygen present in the air, effectively suffocating the fire.
- However, it is not practical to use carbon directly to stop a fire.
4. None of these:
- None of the options mentioned in the given choices is completely correct.
- While water and a damp blanket or sack can be effective in certain situations, they may not be suitable for all types of fires.
- The best course of action to stop a fire depends on the nature and size of the fire, as well as the available resources and safety considerations.
In conclusion, to stop oxygen from reaching the burning material, using a damp blanket or a sack is a viable option. However, it is important to assess the situation and choose the appropriate method based on the specific circumstances.

Answer:

Release of heat and light

• Definition: Release of heat and light refers to the production and emission of thermal energy and electromagnetic radiation in the form of visible light.


• Process: This release occurs as a result of various chemical reactions or physical phenomena.


• Examples: Some common examples include combustion reactions, such as burning of fuels, or the emission of light by luminescent materials.


• Importance: The release of heat and light is essential for various natural and man-made processes, including energy production, lighting, and the functioning of many technological devices.

Options:

• Option A: Carbon: Carbon is a chemical element that is involved in many reactions, but it is not directly responsible for the release of heat and light.


• Option B: Hydrogen: Hydrogen is also involved in various reactions, but it alone does not release heat and light.


• Option C: Light: Light is a form of electromagnetic radiation that is emitted during the release of heat and energy, but it is not the primary product.


• Option D: Energy: Energy is the correct answer as it encompasses the release of heat and light in various forms.

Conclusion:

Therefore, the correct answer is Option D: Energy, as it encompasses the release of heat and light in various forms.

Water should not be sprayed onto an oil fire because:
- Oil and water do not mix: When water is sprayed onto an oil fire, it will sink below the oil and evaporate quickly. This can cause the fire to spread even more as the oil floats on top of the water, carrying the flames with it.
- Risk of steam explosion: The intense heat of an oil fire can cause water to vaporize rapidly, resulting in a steam explosion. This can cause the fire to spread and put people in the vicinity at risk of burns and injuries.
- Lack of cooling effect: Water is not effective in cooling down an oil fire. It does not absorb heat as well as other fire extinguishing agents, such as foam or dry chemical powder. Without proper cooling, the fire can re-ignite quickly.
- Creation of hazardous runoff: Water used on an oil fire can mix with the oil and create a hazardous runoff. This contaminated runoff can flow into drains, waterways, and the environment, causing pollution and potential harm to aquatic life.
- Need for specialized extinguishing agents: To extinguish an oil fire safely and effectively, specialized extinguishing agents, such as foam or dry chemical powder, are required. These agents are designed to smother the fire, prevent re-ignition, and cool down the fuel source effectively.
Conclusion: Spraying water onto an oil fire is not recommended due to the risks involved. It is crucial to use the appropriate fire extinguishing agents and follow proper safety protocols to control and extinguish different types of fires effectively.

Answer:
The three essential components required to make fire are fuel, heat, and oxygen. Here is a detailed explanation of each component:
Fuel:
- Fuel refers to any material that can undergo combustion and sustain a fire.
- It can be in the form of wood, paper, gasoline, oil, or any other flammable substance.
- The fuel provides the necessary energy for the fire to burn.
Heat:
- Heat is the second component required to make fire.
- It is the energy source that raises the temperature of the fuel to its ignition point.
- Heat can be generated through various means, such as a match, a lighter, or friction.
Oxygen:
- Oxygen is the third component necessary for fire to occur.
- It is a gas present in the air, making up about 21% of the Earth's atmosphere.
- During the combustion process, oxygen combines with the fuel, releasing energy in the form of heat and light.
All of These:
- The correct answer to the question is "D: all of these."
- All three components, fuel, heat, and oxygen, are essential for fire to exist.
- Without any one of these components, fire cannot be sustained.
In conclusion, to make fire, you need fuel, heat, and oxygen. The fuel provides the material to burn, heat raises the temperature of the fuel to its ignition point, and oxygen combines with the fuel to release energy in the form of heat and light.