RBSE Solutions Class 8 Science Chapter 18 Carbon and Fuel

Carbon and Fuel Textbook Questions Solved

I. Multiple Choice Questions

Question 1. The coal in which carbon content is highest
(a) Peat
(b) Lignite
(c) Anthracite
(d) Bituminous
Answer: (c) Anthracite
In simple words: Anthracite is a type of coal that has the most carbon in it. This high carbon content makes it burn very hot and clean.

🎯 Exam Tip: Remember the different types of coal and their carbon content; anthracite is known for its purity and high carbon percentage.

Question 2. The residue of fractional distillation of petroleum is
(a) Lubricant oil
(b) Wax
(c) Coal tar
(d) Diesel
Answer: (c) Coal tar
In simple words: After we separate all the lighter parts from petroleum, what is left behind is coal tar. Coal tar is a thick, black liquid.

🎯 Exam Tip: Fractional distillation separates petroleum into different products based on their boiling points, with the heaviest parts remaining as residue.

Question 3. The crystalline allotrope of carbon is
(a) Coal
(b) Kajal
(c) Charcoal
(d) Graphite
Answer: (d) Graphite
In simple words: Carbon can exist in different forms, and graphite is one of the forms that has a regular, crystal-like structure. Diamond is another crystalline allotrope of carbon.

🎯 Exam Tip: Allotropes are different structural forms of the same element; carbon has both crystalline (diamond, graphite) and amorphous allotropes.

Question 2. Fill in the blanks
1. Kerosene is the domestic liquid fuel.
2. In graphite each carbon atom is attached to three nearest carbon atoms while in diamond each carbon atom is attached to four nearest carbon atoms.
Answer:
1. Kerosene
2. three, four
In simple words: Kerosene is a common fuel used at home. In graphite, carbon atoms link to three other atoms, making flat layers. In diamond, each carbon atom links to four other atoms, making a strong 3D structure.

🎯 Exam Tip: Understanding the unique bonding structures in different allotropes of carbon helps explain their different properties, such as hardness and conductivity.

Question 3. Put True (T) for correct and False (F) for incorrect for the following.
1. The carbon content in Lignite is 67%.
2. Peat coal is an example of liquid fuel.
3. Lubricant oil is used as fuel in vehicles and kitchen.
4. The crystalline allotropes of carbon are diamond, graphite and fullerin.
Answer:
1. (T)
2. (F)
3. (F)
4. (T)
In simple words: Check each statement carefully. Lignite has 67% carbon, peat coal is solid, lubricant oil is not fuel, and diamond, graphite, and fullerene are all crystalline forms of carbon.

🎯 Exam Tip: Always read each statement carefully in True/False questions. For example, knowing peat coal is solid helps identify false statements about it being liquid.

Carbon and Fuel Short Answer Type Questions

Question 1. Write the uses of petroleum gas.
Answer: Petroleum gas is mostly used as cooking fuel in homes and as fuel in cars. This makes it very useful for both daily household needs and transportation.
In simple words: Petroleum gas is used for cooking food at home and for running cars.

🎯 Exam Tip: When listing uses, provide specific examples to show a clear understanding of the substance's applications.

Question 2. We should sensibly use petrol and diesel like substances. Explain why?
Answer: We should use petrol and diesel carefully for several important reasons:
1. It takes a very long time and process for natural fuels like petroleum to form.
2. The amounts of these fuels found in the Earth are limited and may only last for about 100 more years.
3. Burning these fuels causes air pollution.
4. They also contribute to global warming, which changes our planet's climate.
In simple words: We should use petrol and diesel wisely because they take millions of years to form, are running out, and cause pollution and global warming.

🎯 Exam Tip: When explaining environmental reasons, remember to link fuel usage directly to both air pollution and global warming, as these are key consequences.

Question 4. Compare L.P.G and Wood as Fuel.
Answer:

🎯 Exam Tip: When comparing fuels, always consider efficiency (heat output vs. time), environmental impact (pollution, ash), and completeness of combustion.

Carbon and Fuel Long Answer Type Questions

Question 1. Draw a well labelled diagram of diamond and graphite and explain their difference.
Answer:
The diagrams below show the structures of diamond and graphite, which are two different forms (allotropes) of carbon.

The main differences between diamond and graphite are outlined in the table below:

🎯 Exam Tip: When describing crystal structures, always mention the bonding (e.g., strong covalent bonds in diamond, weak intermolecular forces between layers in graphite) and its direct impact on properties like hardness and conductivity.

Question 3. The use of petrol, diesel and kerosene is rising day by day. Their smoke is mixing with air and causing air pollution. Write your suggestions and views for reducing air pollution due to use of petroleum.
Answer: Here are some suggestions to help control pollution caused by petroleum use:
1. Use petroleum products carefully and only when necessary.
2. Drive vehicles at a steady and moderate speed as much as possible to save fuel.
3. Turn off the engine when stopped at traffic lights or when waiting somewhere.
4. Make sure your vehicle's tires have the correct air pressure.
5. Regularly maintain your vehicle to ensure it runs efficiently.
6. It is very important to use petroleum products in a way that allows future generations to use them too.
7. Use fuels like unleaded petrol, Compressed Natural Gas (CNG), and Liquefied Petroleum Gas (LPG) to reduce pollution.
In simple words: To reduce pollution, we should use less petrol and diesel, drive steadily, turn off engines when waiting, keep tires properly inflated, maintain vehicles, and choose cleaner fuels like CNG or LPG.

🎯 Exam Tip: When suggesting solutions for environmental problems, include a mix of individual actions (like driving habits), maintenance tips, and policy/alternative fuel considerations.

Question 4. List the fuels used in daily life.
Answer: Many different fuels are used in our daily lives, including:
Wood, coal (like hard coal), dung cakes, and agricultural wastes are common solid fuels. Liquid fuels include kerosene, diesel, petrol, gasoline, and alcohol. Gaseous fuels used are gobar gas (biogas), water gas (\( H_2 + CO \)), producer gas (\( N_2 + CO \)), natural gas, and liquefied petroleum gas (LPG). All these fuels help power our homes, transport, and industries.
In simple words: Everyday fuels include wood, coal, dung cakes, kerosene, diesel, petrol, alcohol, and various gases like LPG, natural gas, and biogas.

🎯 Exam Tip: When listing fuels, try to categorize them (solid, liquid, gas) to demonstrate a systematic understanding of fuel types.

Carbon and Fuel Additional Questions Solved

I. Multiple Choice Questions

Question 1. Which one of the following is petrochemical?
(a) Ammonia
(b) Coke
(c) Acetone
(d) Paraffin Wax
Answer: (d) Paraffin Wax
In simple words: Petrochemicals are chemicals made from petroleum. Paraffin wax is a product derived from petroleum.

🎯 Exam Tip: Petrochemicals are an important category of compounds, so remember key examples that come from petroleum processing.

Question 2. The fossil fuels are
(a) Inexhaustible
(b) Exhaustible
Answer: (b) Exhaustible
In simple words: Fossil fuels like coal, oil, and natural gas take millions of years to form and are used up much faster than they can be made, so they will eventually run out.

🎯 Exam Tip: Understand the difference between exhaustible (limited, non-renewable) and inexhaustible (unlimited, renewable) resources.

Question 4. Main constituent of LPG is
(a) Methane
(b) Butane
(c) Ethane
(d) Propane
Answer: (b) Butane
In simple words: Butane is the main gas found in LPG. This gas is easily compressed and stored, making it a good fuel for homes.

🎯 Exam Tip: Know the primary components of common fuels like LPG and natural gas, as this is a frequent question type.

Question 5. The purest form of carbon is
(a) Coal gas
(b) Coal tar
(c) Coke
(d) Petroleum
Answer: (c) Coke
In simple words: Coke is almost pure carbon, made by heating coal without air. It is very pure compared to other forms listed.

🎯 Exam Tip: Remember that coke is a key product of destructive distillation of coal and is valued for its high carbon content.

Question 6. The natural solid fuel is
(a) Coke
(b) Coal
(c) Coal tar
(d) Coal gas
Answer: (b) Coal
In simple words: Coal is a fossil fuel that is found naturally as a solid in the Earth. It forms from dead plant matter over millions of years.

🎯 Exam Tip: Distinguish between natural fuels (like coal) and processed fuels (like coke, coal tar, coal gas) derived from them.

Question 7. The petroleum product which is used for road surfacing is
(a) Bitumen
(b) Coal gas
(c) Coke
(d) Coal
Answer: (a) Bitumen
In simple words: Bitumen, also called asphalt, is a thick, sticky black substance that comes from petroleum. It is widely used to make roads smooth and durable.

🎯 Exam Tip: Know the various uses of petroleum products beyond just fuel, such as road construction materials.

Question 9. Dead organisms are transformed into petroleum and natural gas in
(a) Absence of air
(b) Presence of air
(c) Presence of sunlight
(d) None of the options
Answer: (a) Absence of air
In simple words: Petroleum and natural gas form deep underground over millions of years when dead plants and animals are squeezed and heated without any oxygen. This process is called anaerobic decomposition.

🎯 Exam Tip: Recall the conditions necessary for fossil fuel formation: high pressure, high temperature, and the absence of oxygen are crucial.

Question 10. Which of these is used as a solvent for dry cleaning
(a) Diesel
(b) Kerosene
(c) Petrol
(d) Paraffin wax
Answer: (c) Petrol
In simple words: Petrol is a good solvent, meaning it can dissolve many substances. This property makes it useful in the dry cleaning process to remove dirt and stains from clothes.

🎯 Exam Tip: Understand that petroleum products have diverse uses; petrol is not just a fuel but also a solvent.

Carbon and Fuel Very Short Answer Type Questions

Question 1. Explain why fossil fuels are exhaustible natural resources?
Answer: Fossil fuels like coal, petroleum, and natural gas are considered exhaustible because they are formed over millions of years from dead organic matter under high pressure and temperature. The rate at which humans use these fuels is much faster than the rate at which they are naturally formed. Once consumed, it takes an extremely long geological time for new reserves to develop, effectively making them non-renewable and finite.
In simple words: Fossil fuels are exhaustible because they take millions of years to form, and we use them up very quickly. This means they cannot be replaced easily once they are gone.

🎯 Exam Tip: When explaining why a resource is exhaustible, emphasize the vast difference between its formation time and its consumption rate.

Question 3. What is meant by carbonisation?
Answer: Carbonisation is the very slow process where dead plant matter buried deep underground slowly turns into coal. This transformation happens over millions of years due to high pressure and heat.
In simple words: Carbonisation is the slow change of dead plants into coal under heat and pressure over a very long time.

🎯 Exam Tip: For definitions, always include the key elements like the material (dead vegetation), the process (slow conversion), and the product (coal).

Question 4. Name the useful products obtained from coal.
Answer: When coal is heated strongly without air, a process called destructive distillation, it produces several useful products. These include coke, which is nearly pure carbon, coal tar, a thick black liquid, and coal gas, which can be used as fuel.
In simple words: From coal, we can get coke, coal tar, and coal gas by heating it without air.

🎯 Exam Tip: Remember the three main products of coal's destructive distillation: coke (solid), coal tar (liquid), and coal gas (gas).

Question 5. Name the different places in India, where natural gas has been formed?
Answer: In India, natural gas reserves are found in several regions. These include Tripura, Jaisalmer in Rajasthan, the offshore areas near Mumbai (Bombay High), and the Krishna-Godavari delta in the Bay of Bengal. These areas are key sources of natural gas for the country.
In simple words: Natural gas in India is found in places like Tripura, Jaisalmer, off the coast of Mumbai, and in the Krishna-Godavari river delta.

🎯 Exam Tip: When asked about geographical locations, try to recall specific states or regions to provide a comprehensive answer.

Carbon and Fuel Short Answer Type Questions

Question 1. What is meant by inexhaustible and exhaustible natural resources?
Answer:
Inexhaustible natural resources are those that are present in endless amounts and will likely not run out due to human activities. Examples include sunlight and air.
Exhaustible natural resources are limited in quantity and can be used up by various human actions. Examples include coal, petroleum, and minerals.
In simple words: Inexhaustible resources are endless, like sunlight, while exhaustible resources are limited and can run out, like coal.

🎯 Exam Tip: Clearly define both terms and provide distinct, well-known examples for each to illustrate your understanding.

Question 2. What is destructive distillation?
Answer: Destructive distillation is a process where organic materials such as wood, coal, or oil are broken down by heating them to high temperatures. This happens in the complete absence of air, leading to the formation of different products.
In simple words: Destructive distillation is when we heat things like wood or coal very hot without air to break them down into other substances.

🎯 Exam Tip: For the definition of destructive distillation, remember the three key components: organic substance, heat, and absence of air.

Question 4. Define combustion. List the substance undergoing complete and incomplete combustion.
Answer:
Combustion is a chemical process where a substance reacts rapidly with oxygen, producing heat and often light. For combustion to occur, three main things are needed: oxygen, a specific (optimum) temperature, and fuel.
Substances undergoing complete combustion include LPG (Liquefied Petroleum Gas), which burns with a blue flame when sufficient oxygen is available.
Substances undergoing incomplete combustion include wood, which burns with a yellow, smoky flame when the oxygen supply is limited.
In simple words: Combustion is burning something with oxygen, making heat and light. You need oxygen, heat, and fuel to burn. LPG burns completely, and wood burns incompletely.

🎯 Exam Tip: When defining a process, always include its key reactants (e.g., oxygen) and products (e.g., heat, light). For examples, link them to the specific type of combustion clearly.

Question 5. Explain the allotropes of carbon.
Answer: Carbon exists in nature in different structural forms, known as allotropes. These allotropes are generally categorized into two main types:
1. Crystalline forms: These have a regular, ordered atomic structure. Examples include:
(a) Diamond
(b) Graphite
2. Amorphous forms: These lack a definite, regular structure. Examples include:
(a) Wood charcoal
(b) Animal charcoal (also known as Bone charcoal)
(c) Coke
(d) Kajal (also called Lamp black)
(e) Gas carbon
In simple words: Allotropes are different forms of carbon. They are either crystal-like (like diamond and graphite) or shapeless (like charcoal and coke).

🎯 Exam Tip: When explaining allotropes, clearly distinguish between crystalline (ordered structure) and amorphous (disordered structure) forms and provide examples for each.

Question 6. How is coal formed?
Answer: Coal is formed over millions of years through a natural process called carbonisation. It begins when ancient forest plants die and are buried under layers of soil and rock due to natural events like floods. Deep underground, these buried plants are exposed to immense heat and pressure, which slowly transforms them into coal.
In simple words: Coal forms when old forest plants get buried under Earth, and over millions of years, heat and pressure turn them into coal.

🎯 Exam Tip: When describing coal formation, emphasize the long time scale, the role of natural processes (burial, heat, pressure), and the origin (dead plants).

Question 7. What is natural gas? Write some of its uses?
Answer: Natural gas is a fossil fuel found deep underground, primarily composed of methane. It is a clean-burning fuel that releases less pollution than coal or oil.
Its main uses include:
1. Fuel for cooking and heating in homes.
2. Generating electricity in power plants.
3. Fuel for vehicles, especially in the form of CNG (Compressed Natural Gas).
4. As a raw material in the production of chemicals and fertilizers.
In simple words: Natural gas is a clean fuel, mainly methane, found underground. It's used for cooking, making electricity, fueling cars, and in factories.

🎯 Exam Tip: When defining natural gas, always mention its primary component (methane) and highlight its cleaner burning properties compared to other fossil fuels.

Question 1. What are the different constituents of petroleum? What are the uses of petroleum products?
Answer: Petroleum, also known as crude oil, is a mixture of various useful substances. The different constituents obtained from petroleum include:
(a) LPG (Liquefied Petroleum Gas)
(b) Petrol (or Gasoline)
(c) Kerosene
(d) Diesel
(e) Lubricating oil
(f) Paraffin wax

The uses of these petroleum products are:
(a) Petrol is used as a fuel for engines in cars and aircraft, and as a solvent for dry cleaning.
(b) Kerosene serves as fuel for stoves, lamps, and jet aircraft.
(c) Diesel powers heavy vehicles and electric generators.
(d) Paraffin wax is used in ointments, candles, and vaseline.
In simple words: Petroleum is made of things like LPG, petrol, kerosene, diesel, lubricating oil, and paraffin wax. These are used for cooking, cars, airplanes, cleaning, and making candles or ointments.

🎯 Exam Tip: When listing constituents and uses, ensure each product is clearly linked to its specific application, showing a detailed understanding of petroleum's versatility.

Question 2. Define the constituents of crude oil.
Answer: Crude oil is a complex mixture made up of many different useful components, often called fractions. These fractions are separated through a process called fractional distillation, where crude oil is heated and its parts evaporate and condense at different temperatures. The main constituents obtained include petroleum gas, gasoline, kerosene, diesel, lubricating oils, paraffin wax, and asphalt.
In simple words: Crude oil has many useful parts inside it. These parts are separated by heating the oil, and they include things like petrol, diesel, and wax.

🎯 Exam Tip: When defining crude oil constituents, always mention fractional distillation as the key process for separation.

Question 3. What is PCRA? What are its advices?
Answer:
PCRA stands for Petroleum Conservation Research Association. It is an organization dedicated to conserving petroleum and promoting the efficient use of fuel, considering both economic benefits and environmental protection.
The main advice from PCRA for saving fuel includes:
1. Drive at a steady and moderate speed whenever possible.
2. Turn off the vehicle's engine when stopped at traffic lights or when waiting.
3. Make sure the tires have the correct air pressure.
In simple words: PCRA is a group that helps people save fuel for money and the environment. They suggest driving steadily, turning off engines when stopped, and keeping tires properly inflated.

🎯 Exam Tip: For organizational questions, remember both the full form of the acronym and its primary objectives, along with practical tips it provides.

I. Multiple Choice Questions

Question 1.
1. The coal in which carbon content is highest
(a) Peat
(b) Lignite
(c) Anthracite
(d) Bituminous
2. The residue of fractional distillation of petroleum is
(a) Lubricant oil
(b) Wax
(c) Coal tar
(d) Diesel
3. The crystalline allotrope of carbon is
(a) Coal
(b) Kajal
(c) Charcoal
(d) Graphite
Answer:
1. (c) Anthracite
2. (c) Coal tar
3. (d) Graphite
In simple words: Anthracite coal has the most carbon, making it a high-quality fuel. Coal tar is what remains after petroleum is distilled. Graphite is a crystalline form of carbon.

🎯 Exam Tip: Remember key properties of different coal types, petroleum products, and carbon allotropes to quickly identify correct answers in multiple-choice questions.

Question 2. Fill in the blanks
1. .............is the domestic liquid fuel.
2. In graphite each carbon atom is attached to................nearest carbon atoms while in diamond each carbon atom is attached to...........nearest carbon atoms.
Answer:
1. Kerosene
2. three, four
In simple words: Kerosene is a common liquid fuel for homes. In graphite, carbon atoms link to three others, but in diamond, they link to four others.

🎯 Exam Tip: Pay attention to unique properties and uses of different substances, and structural differences in materials like carbon allotropes, for fill-in-the-blank questions.

Question 3. Put True (T) for correct and False (F) for incorrect for the following.
1. The carbon content in Lignite is 67%.
2. Peat coal is an example of liquid fuel.
3. Lubricant oil is used as fuel in vehicles and kitchen.
4. The crystalline allotropes of carbon are diamond, graphite and fullerin.
Answer:
1. (T)
2. (F)
3. (F)
4. (T)
In simple words: It is true that lignite has about 67% carbon and that diamond, graphite, and fullerene are crystalline carbon forms. It is false that peat coal is liquid fuel or that lubricant oil is used as fuel.

🎯 Exam Tip: Understand the basic characteristics and applications of various fuels and carbon forms to differentiate between true and false statements accurately.

Carbon And Fuel Short Answer Type Questions

Question 1. Write the uses of petroleum gas.
Answer: Petroleum gas, often known as LPG, is mainly used as a cooking fuel in homes. It also serves as a fuel for certain types of vehicles. This makes it a versatile energy source.
In simple words: Petroleum gas is mostly used for cooking at home and as fuel in some cars.

🎯 Exam Tip: When asked for uses, list the primary applications and mention different sectors where it's utilized for a comprehensive answer.

Question 2. We should sensibly use petrol and diesel like substances. Explain why?
Answer: We should use fuels like petrol and diesel carefully because of several important reasons.
1. These natural fuels take millions of years to form in the earth.
2. Their existing reserves are very limited and might only last for about another 100 years.
3. Burning them releases harmful substances that cause air pollution.
4. This pollution also adds to global warming, which is changing our planet's climate.
In simple words: We must use petrol and diesel wisely. They take a very long time to form and will soon run out. Also, they make the air dirty and cause the Earth to get hotter.

🎯 Exam Tip: For "explain why" questions, provide clear, concise points with both environmental and resource-related arguments to support your answer.

Question. Compare L.P.G and Wood as Fuel.
Answer:

🎯 Exam Tip: When comparing, always use a table format to clearly show the differences between two items side-by-side, covering the same aspects for both.

Carbon And Fuel Long Answer Type Questions

Question 1. Draw a well labelled diagram of diamond and graphite and explain their difference.
Answer:

The main differences between diamond and graphite are as follows:

🎯 Exam Tip: When drawing diagrams, ensure they are clear and well-labeled. For comparisons, always present the information in a table format to highlight differences effectively.

Question 3. The use of petrol, diesel and kerosene is rising day by day. Their smoke is mixing with air and causing air polution. Write your suggestions and views for reducing air pollution.
Answer: Here are some suggestions to control pollution caused by the use of petroleum:
1. Petroleum should be used economically and judiciously.
2. Drive vehicles at a constant and moderate speed as far as possible.
3. Switch off the engine at traffic lights or at a place where you have to wait.
4. Ensure correct pressure in tyres.
5. Ensure regular maintenance of the vehicle.
6. Sustainable use of petroleum products is a must so that future generations may also use them.
7. Use unleaded petrol, CNG, LPG to minimise pollution.
In simple words: To reduce pollution from fuels, use petrol and diesel carefully. Drive at a steady speed, turn off your engine when waiting, keep tires inflated, and maintain your vehicle. Also, use cleaner fuels like CNG or LPG.

🎯 Exam Tip: When providing suggestions, focus on practical, actionable steps that individuals and society can take. Grouping similar ideas can also help make your answer clearer.

Question 4. List the fuels used in daily life.
Answer: Many different types of fuels are used in our daily lives. These include solid fuels like wood, coal, dried dung cakes, and agricultural waste. Liquid fuels such as kerosene, diesel, petrol, gasoline, and alcohol are also common. Gaseous fuels like gobar gas, water gas \( (\text{H}_2 + \text{CO}) \), producer gas \( (\text{N}_2 + \text{CO}) \), natural gas, and LPG (Liquefied Petroleum Gas) are widely used for various purposes.
In simple words: Common fuels we use are wood, coal, dung cakes (solid fuels), kerosene, diesel, petrol, alcohol (liquid fuels), and gobar gas, natural gas, and LPG (gaseous fuels).

🎯 Exam Tip: When listing items, try to categorize them (e.g., solid, liquid, gas) to demonstrate a systematic understanding. Include a diverse range of examples.

Question 6.. Differentiate between complete and incomplete combustion. Explain with example.
Answer:
Complete combustion: When a sufficient amount of oxygen is supplied to a burning substance, it burns with a blue flame, and this is called complete combustion. For example, the combustion of LPG (Liquefied Petroleum Gas).
Incomplete combustion: When any burning substance does not get a sufficient amount of oxygen supply, it burns with a yellow flame. This is called incomplete combustion. For example, burning wood that causes air pollution.
In simple words: Complete burning happens when there is enough oxygen, producing a blue flame (like LPG). Incomplete burning happens with less oxygen, making a yellow flame and often causing smoke (like burning wood, which pollutes the air).

🎯 Exam Tip: Clearly define each type of combustion, highlight the key difference (oxygen supply), and provide a distinct, common example for both to illustrate your understanding.

I. Multiple Choice Questions

Question 1. Which one of the following is petrochemical?
(a) Ammonia
(b) Coke
(c) Acetone
(d) Paraffin Wax
Answer: (c) Acetone
In simple words: Acetone is a chemical made from petroleum. It's a petrochemical.

🎯 Exam Tip: Understand common petrochemicals and their origins. Petrochemicals are chemicals derived from petroleum or natural gas.

Question 2. The fossil fuels are
(a) Inexhaustible
(b) Exhaustible
Answer: (b) Exhaustible
In simple words: Fossil fuels can run out because they are limited, making them exhaustible resources.

🎯 Exam Tip: Remember that fossil fuels are formed over millions of years and are finite, which means they are exhaustible resources.

Question 4. Main constituent of LPG is
(a) Methane
(b) Butane
(c) Ethane
(d) Propane
Answer: (b) Butane
In simple words: Butane is the main part of LPG, which is a common cooking gas.

🎯 Exam Tip: Know the primary components of common fuels like LPG; while butane is the main constituent, propane is also a significant part.

Question 5. The purest form of carbon is
(a) Coal gas
(b) Coal tar
(c) Coke
(d) Petroleum
Answer: (c) Coke
In simple words: Coke is a very pure kind of carbon, made from coal.

🎯 Exam Tip: Recall that coke is obtained from coal through destructive distillation and is known for its high carbon content and purity.

Question 6. The natural solid fuel is
(a) Coke
(b) Coal
(c) Coal tar
(d) Coal gas
Answer: (b) Coal
In simple words: Coal is a natural solid fuel found in the ground.

🎯 Exam Tip: Distinguish between primary natural fuels (like coal) and refined or processed fuels (like coke, coal tar, coal gas).

Question 7. The petroleum product which is used for road surfacing is
(a) Bitumen
(b) Coal gas
(c) Coke
(d) Coal
Answer: (a) Bitumen
In simple words: Bitumen, from petroleum, is used to make roads. It is black and sticky.

🎯 Exam Tip: Connect specific petroleum products to their common applications, such as bitumen for roads.

Question 9. Dead organisms are transformed into petroleum and natural gas in
(a) Absence of air
(b) Presence of air
(c) Presence of sunlight
(d) None of the options
Answer: (a) Absence of air
In simple words: Petroleum and natural gas are made from dead plants and animals underground without air. No air is key for them to change.

🎯 Exam Tip: Remember that the formation of fossil fuels requires anaerobic (absence of air) conditions, along with high pressure and temperature over millions of years.

Question 10. Which of these is used as a solvent for dry cleaning
(a) Diesel
(b) Kerosene
(c) Petrol
(d) Paraffin wax
Answer: (c) Petrol
In simple words: Petrol is used to dissolve dirt in dry cleaning because it works well and dries fast.

🎯 Exam Tip: Know the common uses of various petroleum products; petrol (gasoline) is effective as a solvent due to its ability to dissolve oils and fats.

Carbon And Fuel Very Short Answer Type Questions

Question 1. Explain why fossil fuels are exhaustible natural resources?
Answer: Calorific value is the amount of heat released when a certain amount of fuel burns completely. It helps us know how much energy a fuel can provide.
In simple words: Calorific value tells us how much heat a fuel gives when it burns fully.

🎯 Exam Tip: When defining scientific terms, ensure your explanation is clear, concise, and directly addresses the core meaning of the term.

Question 3. What is meant by carbonisation?
Answer: Carbonisation is the very slow natural process where dead plants and trees buried deep underground gradually change into coal. This transformation takes millions of years due to heat and pressure.
In simple words: Carbonisation is when old plants slowly turn into coal underground over a very long time.

🎯 Exam Tip: Define carbonisation by explaining the raw materials (dead vegetation), the conditions (heat, pressure, burial), and the end product (coal), along with the time frame.

Question 4. Name the useful products obtained from coal.
Answer: When coal is heated strongly without air, a process called destructive distillation occurs. This process gives us useful products like coke, which is a pure form of carbon, along with coal tar and coal gas. These products have various industrial uses.
In simple words: From coal, we can get coke, coal tar, and coal gas when it's heated without air.

🎯 Exam Tip: Focus on the specific products derived from coal through destructive distillation (coke, coal tar, coal gas) as these are key terms.

Question 5. Name the different places in India, where natural gas has been formed?
Answer: In India, significant deposits of natural gas have been discovered and formed in several regions. These include Tripura, Jaisalmer in Rajasthan, and the offshore areas near Mumbai. Additionally, natural gas is found in the Krishna-Godavari delta.
In simple words: Natural gas is found in India in places like Tripura, Jaisalmer, near Mumbai (in the sea), and in the Krishna-Godavari delta area.

🎯 Exam Tip: For geographical questions, remember specific names of locations where resources are found. Being precise with names helps score better.

Carbon And Fuel Short Answer Type Questions

Question 1. What is meant by inexhaustible and exhaustible natural resources?
Answer: Natural resources are categorized into two types: inexhaustible and exhaustible. Inexhaustible resources are found in endless amounts and will not run out due to human actions; examples include sunlight and air. Exhaustible resources, on the other hand, are limited in quantity and can be used up by human activities over time; examples include coal, petroleum, and minerals.
In simple words: Inexhaustible resources, like sun and air, are endless. Exhaustible resources, like coal and petrol, are limited and can run out.

🎯 Exam Tip: Clearly define each type of resource and provide at least two distinct examples for each to illustrate your understanding fully.

Question 2. What is destructive distillation?
Answer: Destructive distillation is a process where organic materials, such as wood, coal, or oil, are heated to very high temperatures. This heating happens in an environment completely free of air, causing the substances to break down into simpler components. This method is used to get various useful products from these materials.
In simple words: Destructive distillation is when wood, coal, or oil is heated a lot without any air. This breaks them down into different things.

🎯 Exam Tip: When defining destructive distillation, emphasize the key condition of "absence of air" and mention the purpose of breaking down organic substances into other useful products.

Question 4. Define combustion. List the substance undergoing complete and incomplete combustion.
Answer: Combustion is a chemical reaction that takes place when oxygen mixes with other materials. This reaction typically creates heat and often light. For any material to burn, three main things are needed: first, oxygen; second, the right temperature (not too cold); and third, the fuel itself.
In simple words: Combustion is burning. It happens when oxygen meets a material, making heat and light. You need oxygen, the right heat, and fuel for it to burn.

🎯 Exam Tip: A good definition of combustion should include the reactants (fuel, oxygen), products (heat, light), and essential conditions for the reaction to occur.

Question 5. Explain the allotropes of carbon.
Answer: Carbon exists in various natural forms, known as allotropes, which are mainly grouped into two categories. The first is crystalline forms, where atoms have a regular, repeating structure; examples include diamond and graphite. The second category is amorphous forms, which lack a definite crystalline structure; these include wood charcoal, animal charcoal (also called bone charcoal), coke, kajal (lamp black), and gas carbon.
In simple words: Carbon comes in different forms called allotropes. Some are crystalline, like diamond and graphite, where atoms are neatly arranged. Others are amorphous, like charcoal, coke, and kajal, where atoms are not neatly arranged.

🎯 Exam Tip: When explaining allotropes, categorize them (crystalline, amorphous) and provide clear examples for each, briefly mentioning their structural differences if possible.

Question 6. How is coal formed?
Answer: Coal is a fossil fuel that forms over an extremely long period, typically millions of years. It begins when ancient forest trees and other plant matter get buried deep beneath the Earth's surface, often due to natural events like floods or earthquakes. Over time, the intense heat and pressure from the overlying layers of earth slowly transform these buried plants into coal.
In simple words: Coal forms when old forest trees are buried deep in the ground for millions of years. Heat and pressure slowly turn these plants into coal.

🎯 Exam Tip: Describe coal formation as a long, geological process involving burial of organic matter, and the action of heat and pressure over millions of years.

Question 1. What are the different constituents of petroleum? What are the uses of petroleum products?
Answer: Petroleum is a complex mixture from which several useful products are obtained. Its main components include Liquefied Petroleum Gas (LPG), petrol, kerosene, diesel, lubricating oil, and paraffin wax. These products have diverse applications: Petrol is used as fuel for vehicles, aircraft, and in dry cleaning. Kerosene serves as fuel for stoves, lamps, and jet engines. Diesel powers heavy vehicles and electric generators. Paraffin wax is utilized in making ointments, candles, and vaseline.
In simple words: Petroleum has many parts like LPG, petrol, kerosene, diesel, lubricating oil, and paraffin wax. Petrol fuels cars and planes. Kerosene is for lamps and stoves. Diesel runs big vehicles and generators. Paraffin wax is used for ointments and candles.

🎯 Exam Tip: List the major constituents and for each, provide one or two key uses. This shows a comprehensive understanding of petroleum products.

Question 2. Define the constituents of crude oil.
Answer: Crude oil consists of many useful fractions which can be obtained by subjecting it to the process of fractional distillation. These include petroleum gas, gasoline, kerosene, diesel, lubricating oils, paraffin wax and asphalt.
In simple words: Crude oil is a mix of many parts. We get these parts, like petrol, diesel, and wax, by heating the crude oil in a special way.

🎯 Exam Tip: When defining crude oil constituents, mention that they are separated through fractional distillation and list the common fractions obtained from this process.

Question 3. What is PCRA? What are its advices?
Answer: PCRA stands for the Petroleum Conservation Research Association. This organization works to save petroleum and promotes using fuel wisely, both to save money and protect the environment. PCRA offers several tips to help save fuel:
1. Drive at a constant and moderate speed as far as possible.
2. Switch off the engine at traffic lights or at a place where you have to wait.
3. Ensure current tyre pressure.
In simple words: PCRA is an organization that helps us save petroleum and use fuel smartly. Their tips are: drive at a steady speed, turn off your engine when waiting, and keep tires filled correctly.

🎯 Exam Tip: When explaining an acronym, spell out the full name first. Then, summarize its mission and list its key recommendations clearly.