Key Concept: Inexhaustible Natural Resources

c) Sunlight

[Solution Description]

Inexhaustible natural resources are those that are present in unlimited quantity in nature and are not likely to be exhausted by human activities. Examples include sunlight and air. Therefore, the correct answer is sunlight.

Key Concept: Natural Resources

c) Soil

[Solution Description]

Natural resources are materials or substances that occur in nature and can be used for economic gain. They include air, water, soil, minerals, forests, wildlife, etc.

Key Concept: Exhaustible Natural Resources

b) Wildlife

[Solution Description]

Exhaustible natural resources are those whose amount in nature is limited and can be exhausted by human activities. Examples include forests, wildlife, minerals, coal, petroleum, and natural gas.

Key Concept: Inexhaustible Natural Resources

c) Sunlight

[Solution Description]

Inexhaustible natural resources are those that are present in unlimited quantities and cannot be exhausted by human activities. Examples include sunlight and air.

Key Concept: Exhaustible Natural Resources

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that coal and petroleum are exhaustible natural resources, which is true because they are present in limited quantities in nature. The reason states that they are formed from the dead remains of living organisms over millions of years and are present in limited quantities. This is also true. Moreover, the reason correctly explains why coal and petroleum are exhaustible, as their formation is a very slow process and their reserves are finite. Therefore, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Conservation of Petroleum

c) Ensure correct tyre pressure

[Solution Description]

The Petroleum Conservation Research Association (PCRA) advises several practices to conserve petrol/diesel while driving. These include maintaining a constant and moderate speed, switching off the engine at traffic lights or when waiting, ensuring correct tyre pressure, and regular vehicle maintenance. Among the given options, maintaining correct tyre pressure is one of the recommended practices.

Key Concept: Resource Depletion Analysis

c) 200 units

[Solution Description]

Let the initial resource be $R$. Each generation consumes an equal fraction of the remaining resource. After three generations, the remaining resource is 125 units.

Let each generation consume $x$ units. After the first generation: $R - x$.

After the second generation: $(R - x) - x = R - 2x$.

After the third generation: $(R - 2x) - x = R - 3x$.

Given that the final remaining resource is 125 units: $R - 3x = 125$.

To find the relationship between $R$ and $x$, assume each generation consumes half of the remaining resource:

First generation: $x = \frac{R}{2}$.

Second generation: $x = \frac{R - x}{2} = \frac{R - \frac{R}{2}}{2} = \frac{R}{4}$.

Third generation: $x = \frac{R - \frac{R}{2} - \frac{R}{4}}{2} = \frac{R}{8}$.

Substituting into the equation $R - 3x = 125$: $R - 3 \times \frac{R}{8} = 125$.

Simplifying: $R - \frac{3R}{8} = 125$ $\Rightarrow$ $\frac{5R}{8} = 125$.

Solving for $R$: $R = 125 \times \frac{8}{5} = 200$ units.

Key Concept: Coal Formation

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that coal is formed from the remains of vegetation that got buried under soil millions of years ago. This is true as per the syllabus, which explains that coal is formed from dense forests that got buried due to natural processes like flooding. The reason states that the process of conversion of dead vegetation into coal is called carbonisation. This is also true as carbonisation is the term used to describe this slow process under high pressure and temperature. Moreover, the reason correctly explains the assertion, as carbonisation is the specific process by which dead vegetation is converted into coal.

Key Concept: Coal Formation

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description] Coal is indeed a fossil fuel, as it is formed from the remains of vegetation that got buried under soil millions of years ago. This vegetation underwent a process called carbonisation, where it was subjected to high pressure and temperature over time, converting it into coal. Therefore, both the Assertion and Reason are true, and the Reason correctly explains the Assertion.

Key Concept: Uses of Coal

b) To produce steam

[Solution Description]

Historically, coal was used in railway engines to produce steam, which powered the engine. This was a common practice before the advent of diesel and electric engines.

Key Concept: Coal Gas

c) As a fuel in industries

[Solution Description]

Coal gas is obtained during the processing of coal to get coke. It is primarily used as a fuel in many industries situated near the coal processing plants.

Key Concept: Formation of Coal, Carbonisation

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that coal is formed from the remains of dead vegetation under high pressure and temperature over millions of years. This is correct as coal is indeed a fossil fuel formed from the compression and decomposition of plant material in the absence of air, under high pressure and temperature over geological time scales.

The reason states that the process of carbonisation involves the conversion of dead plants into coal due to the presence of carbon. This is also correct because carbonisation is the chemical process by which dead vegetation is transformed into coal, primarily through the increase in carbon content and the loss of other elements like hydrogen and oxygen.

Moreover, the reason correctly explains the assertion because it describes the specific process (carbonisation) by which dead vegetation is converted into coal, which aligns with the assertion about the formation of coal from dead vegetation under specific conditions.

Therefore, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Formation of Coal

c) Carbonisation

[Solution Description]

The process by which dead vegetation is converted into coal over millions of years under high pressure and temperature is called carbonisation. This occurs as dead plants get buried under soil, compressed, and subjected to rising temperatures, leading to the formation of coal.

Key Concept: Fossil Fuel, Carbonisation, Coal Formation

b) It is formed from the remains of ancient plants

[Solution Description]

Coal is referred to as a fossil fuel because it is formed from the remains of ancient vegetation that lived millions of years ago. Over time, these plants were buried under layers of soil and sediment. Under high pressure and temperature, the organic matter was transformed into coal through the process of carbonisation. Since coal originates from the fossilised remains of plants, it is classified as a fossil fuel.

Key Concept: Coal as a Fossil Fuel

b) It is derived from the remains of ancient plants

[Solution Description]

Coal is called a fossil fuel because it is formed from the remains of vegetation that existed millions of years ago. These plants were buried under soil and subjected to high pressure and temperature, leading to their slow transformation into coal. Since it originates from ancient organic matter, coal is classified as a fossil fuel.

Key Concept: Carbonisation Process

c) Carbonisation

[Solution Description]

The process where dead vegetation is converted into coal under high pressure and temperature is known as carbonisation. This process takes millions of years and results in the formation of coal, which is primarily composed of carbon.

Key Concept: Fossil Fuels

c) It was formed from dead organisms millions of years ago

[Solution Description]

Coal is classified as a fossil fuel because it was formed from the remains of dead plants that lived millions of years ago. These remains underwent chemical changes under high pressure and temperature, leading to the formation of coal.

Key Concept: Exhaustible Resource

c) They take millions of years to form and are consumed at a faster rate

[Solution Description]

Fossil fuels are considered exhaustible resources because they take millions of years to form and the rate at which we consume them is much faster than the rate at which they are naturally replenished. This makes their availability finite.

Key Concept: Coal Formation, Fossil Fuels

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

Coal is indeed a fossil fuel formed from the remains of ancient plants. The process of coal formation, known as carbonisation, occurs when dead vegetation is buried under soil and subjected to high pressure and temperature over millions of years. This process converts the plant material into coal, which is rich in carbon. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Coal Tar, Uses

c) Bitumen

[Solution Description]

Coal tar is used to produce synthetic dyes, drugs, perfumes, and naphthalene balls. However, bitumen, which is used for metalling roads, is derived from petroleum, not coal tar.

Key Concept: Uses of Coal

b) As a fuel

[Solution Description]

Coal is used as a fuel in various industries. It is also processed to produce coke, coal tar, and coal gas, which are further used in manufacturing and other industrial applications.

Key Concept: Products of Coal Processing

c) Carbon

[Solution Description]

Coke is a tough, porous, and black substance obtained from the processing of coal. It is an almost pure form of carbon, which makes it suitable for use in steel manufacturing and metal extraction processes.

Key Concept: Uses of Coal

d) Making synthetic diamonds

[Solution Description]

Coal has been used in railway engines to produce steam, in thermal power plants to generate electricity, and as a fuel in industries. Cooking food with coal is also a common use.

Key Concept: Coal Formation, Cooking Fuel

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The Assertion states that coal is a fossil fuel formed from the remains of vegetation under high pressure and temperature over millions of years. This is true as coal is indeed formed from the remains of plants that underwent carbonisation. The Reason explains that the process of carbonisation involves the conversion of dead vegetation into coal due to high pressure and temperature. This is also true and correctly explains why coal is considered a fossil fuel. Therefore, both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Key Concept: Formation of Coal

c) Carbonisation

[Solution Description]

The slow process of conversion of dead vegetation into coal under high pressure and temperature is called carbonisation. This occurs due to the compression and heating of plant material over millions of years.

Key Concept: Coal processing, Coke

a) 2940 kg

[Solution Description]

First, calculate the mass of iron in 5000 kg of steel:

Mass of iron = $5000 \, \text{kg} \times 0.98 = 4900 \, \text{kg}$.

Using the ratio of coke to iron ore:

For 1000 kg of iron ore, 600 kg of coke is required.

Therefore, the amount of coke required for 4900 kg of iron:

$\frac{4900 \, \text{kg}}{1000 \, \text{kg}} \times 600 \, \text{kg} = 2940 \, \text{kg}$.

Key Concept: Coal Processing

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that coke is a product obtained from coal processing and is used in steel manufacturing. This is true as coke is indeed produced from coal and is widely used in steel production due to its high carbon content. The reason states that coke is an almost pure form of carbon, making it suitable for high-temperature processes. This is also true because coke's purity allows it to burn at very high temperatures, which is essential for processes like steel manufacturing. Moreover, the reason correctly explains why coke is used in steel production, as its high carbon content and ability to withstand high temperatures are crucial for this application. Therefore, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Coal Tar, Industrial Products

b) Natural rubber

[Solution Description]

Coal tar is used to produce synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials, and naphthalene balls. However, it is not used to produce natural rubber, which is derived from rubber trees.

Key Concept: Coke, Coal Gas

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that coke is used in the extraction of metals due to its high carbon content and porous nature. This is true because coke, being an almost pure form of carbon, acts as a reducing agent in metallurgical processes. The reason explains that the porous nature of coke allows it to react efficiently with metal oxides, which is also true. Furthermore, the reason correctly explains why coke is used in metal extraction, as its porosity enhances its reactivity with metal oxides, facilitating the reduction process.

Key Concept: Coke, Coal Gas

c) Coke is a porous, black substance used in steel manufacturing.

[Solution Description]

During the processing of coal, coke and coal gas are both produced. Coke is an almost pure form of carbon and is used in the manufacture of steel and extraction of metals. Coal gas is obtained as a byproduct and is used as a fuel in industries. Therefore, the correct statement should reflect these facts.

Key Concept: Uses of Coke

b) In the manufacture of steel

[Solution Description]

Coke is primarily used in the manufacture of steel and in the extraction of many metals.

Key Concept: Coke, Extraction of Metals

d) Acts as a reducing agent

[Solution Description]

The primary function of coke in the extraction of iron is to act as a reducing agent. It reacts with the oxygen in the iron oxide to produce carbon dioxide and elemental iron. The chemical reaction can be represented as:

$\text{Fe}_2\text{O}_3 + 3\text{C} \rightarrow 2\text{Fe} + 3\text{CO}$

Here, coke (carbon) reduces the iron oxide to iron.

Key Concept: Coke

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

The assertion states that coke is used in the extraction of many metals because it is a tough, porous, and black substance. This is true as coke's properties make it suitable for such applications. The reason states that coke is an almost pure form of carbon, which is also true. However, the reason does not directly explain why coke is used in metal extraction; it only describes its composition. Therefore, both statements are true, but the reason is not the correct explanation of the assertion.

Key Concept: Coke

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

Solution: The assertion states that coke is a tough, porous, and black substance, which is true as per the syllabus. The reason states that coke is used in the manufacture of steel and in the extraction of many metals, which is also true. However, the reason does not explain why coke is tough, porous, and black. Therefore, both assertion and reason are true, but the reason is not the correct explanation of the assertion.

Key Concept: Coke, Coal Processing

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that coke is used in the extraction of metals because it is a reducing agent. This is true as coke, being rich in carbon, acts as a reducing agent by providing electrons to metal oxides, thereby reducing them to pure metals. The reason given is that coke contains almost pure carbon, which can react with metal oxides to extract metals. This is also true and directly explains why coke is used as a reducing agent in metal extraction. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Coke

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

The assertion states that coke is an almost pure form of carbon, which is true as per the syllabus. The reason given is that coke is used in the extraction of many metals, which is also true. However, the reason does not explain why coke is an almost pure form of carbon. Therefore, both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

Key Concept: Coke in Steel Manufacturing

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

The assertion states that coke is used in steel manufacturing as a reducing agent, which is true. Coke reacts with iron ore to reduce iron oxide to iron. The reason claims that coke removes impurities by reacting with oxygen, which is also true. However, the reason does not correctly explain why coke is specifically used in steel manufacturing. The primary role of coke in steel production is its ability to reduce iron oxide to iron, not just removing impurities. Therefore, both statements are true, but the reason is not the correct explanation of the assertion.

Key Concept: Coke, Steel Manufacturing

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description] Coke is a tough, porous, and almost pure form of carbon. In the extraction of iron from its ore (iron oxide), coke plays a crucial role as a reducing agent. When coke is heated with iron ore in a blast furnace, it reacts with oxygen to form carbon monoxide. This carbon monoxide then reduces the iron oxide to iron. Thus, the assertion that coke is used as a reducing agent in the extraction of iron from its ore is true. The reason that coke provides the necessary carbon monoxide for the reduction process is also true and correctly explains the assertion.

Key Concept: Uses of Coal Tar

c) Bitumen

[Solution Description]

Products obtained from coal tar include synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials, and naphthalene balls. Bitumen, however, is a petroleum product used in place of coal-tar for metalling the roads.

Key Concept: Coal Tar, Applications

a) Food Industry

[Solution Description]

Coal tar is used in the production of synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, and roofing materials. However, it is not typically used in the food industry due to its chemical nature and potential health hazards. Therefore, the food industry would least likely use products derived from coal tar.

Key Concept: Uses of Coal Tar

b) For making synthetic dyes

[Solution Description]

Coal tar is used as a starting material for manufacturing various substances used in everyday life, such as synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, and roofing materials.

Key Concept: Coal Tar, Industrial Applications

c) Agriculture industry

[Solution Description]

Products derived from coal tar are used in various industries such as pharmaceuticals, plastics, paints, and photography. However, coal tar products are not typically used in the agriculture industry for crop production.

Key Concept: Coal Tar and its Products

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

The assertion states that coal tar is a mixture of about 200 substances, which is correct as per the syllabus. The reason states that coal tar is used as a starting material for manufacturing synthetic dyes, drugs, and perfumes, which is also correct. However, the reason does not explain why coal tar is a mixture of about 200 substances; it only describes one of its uses. Therefore, both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

Key Concept: Coal Tar, Synthetic Dyes

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that synthetic dyes are extensively used in the textile industry because they are derived from coal tar. This is true as synthetic dyes are indeed manufactured from coal tar derivatives. The reason states that coal tar is a complex mixture of about 200 substances, making it a versatile starting material for various industrial products. This is also true as coal tar's complex composition allows it to be used in the production of numerous substances, including synthetic dyes. Moreover, the reason correctly explains why coal tar is suitable for producing synthetic dyes, as its diverse composition provides the necessary raw materials. Therefore, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Coal Tar

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

The assertion states that coal tar is used as a starting material in the production of synthetic dyes and drugs. This is true as coal tar is indeed a key raw material for these products. The reason given is that coal tar is a mixture of about 200 substances, making it suitable for diverse industrial applications. This is also true because the complex composition of coal tar allows it to be used in various industries, including the production of synthetic dyes and drugs. However, the reason does not directly explain why coal tar is specifically used for synthetic dyes and drugs. It only explains its general suitability for industrial applications due to its complex composition. Therefore, both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

Key Concept: Coal and Petroleum, Synthetic Products

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

Coal tar is a byproduct of coal processing and contains numerous aromatic compounds such as benzene, toluene, and naphthalene. These aromatic compounds are crucial intermediates in the synthesis of complex organic molecules. In the production of synthetic dyes, these compounds undergo chemical reactions to form chromophores, which are responsible for color. Similarly, in pharmaceuticals, aromatic compounds serve as building blocks for active pharmaceutical ingredients (APIs). Therefore, the assertion that coal tar is used in the production of synthetic dyes and drugs due to its aromatic compounds is true. The reason correctly explains why these aromatic compounds are essential for synthesizing complex organic molecules used in dyes and drugs. Hence, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Coal Tar Products

c) As an insect repellent

[Solution Description]

Naphthalene balls are primarily used as insect repellents to repel moths and other insects. They are obtained from coal tar, which is a thick, black liquid with an unpleasant smell.

Key Concept: Coal Tar Applications

b) Pharmaceutical industry

[Solution Description]

Products derived from coal tar are used in various industries, including the pharmaceutical industry for manufacturing drugs.

Key Concept: Coal Gas, Historical Usage

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

The assertion states that coal gas was primarily used for street lighting in London and New York during the early 19th century. This is true as historical records indicate that coal gas was indeed used for street lighting in these cities around 1810 and 1820, respectively. The reason states that coal gas is obtained during the processing of coal to get coke and it was a readily available source of heat. While it is true that coal gas is obtained during the processing of coal to get coke, the reason does not directly explain why it was used for street lighting. Instead, it was used for lighting due to its ability to produce a bright flame, not just because it was a source of heat.

Key Concept: Coal Gas Production, Efficiency

c) 70,000 m$^3$

[Solution Description]

First, calculate the daily gas production: $500 \text{ m}^3/\text{ton} \times 20 \text{ tons} = 10,000 \text{ m}^3/\text{day}$. Then, multiply by the number of days in a week: $10,000 \text{ m}^3/\text{day} \times 7 \text{ days} = 70,000 \text{ m}^3$.

Key Concept: Coal Processing Products

(B) Both (A) and (R) are true, but (R) is not the correct explanation of (A).

[Solution Description]

• Coke is a nearly pure form of carbon, obtained as a by-product when coal is heated strongly in the absence of air during the destructive distillation of coal. It is widely used in the manufacture of steel due to its high carbon content and reducing properties.
• Coal gas is another by-product obtained during this process, along with coal tar and ammoniacal liquor.
• The statement (R) correctly mentions that coke is obtained during coal processing, but its main purpose is not just coal gas production—rather, it is one of the multiple by-products.

Key Concept: Coal Gas, Coal Tar

b) Coal Gas

[Solution Description]

Coal gas is obtained during the processing of coal to get coke. It was used for street lighting for the first time in London in 1810 and in New York around 1820. Nowadays, it is used as a source of heat rather than light. Coal tar, however, is primarily used for manufacturing various substances like synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials, etc., and not for lighting or heating purposes.

Key Concept: Coal Tar

c) Bitumen[Solution Description]Coal tar is a black, thick liquid used as a starting material for manufacturing various substances like synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials, and naphthalene balls. Bitumen, a petroleum product, is used for metalling roads instead of coal tar.

Key Concept: Coal Tar

b) Bitumen

[Solution Description]

Bitumen, which is a petroleum product, is now commonly used in place of coal-tar for metalling the roads due to its effectiveness and availability.

Key Concept: Petroleum Formation and Refining

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

The assertion states that petroleum is formed from the remains of sea organisms over millions of years under high pressure and temperature, which is true as per the syllabus. The reason states that the process of refining petroleum separates it into various useful constituents like petrol, diesel, and lubricating oil, which is also true. However, the reason does not explain the formation of petroleum; it explains what happens after petroleum is formed. Therefore, both statements are true, but the reason is not the correct explanation of the assertion.

Key Concept: Petroleum Formation, Location

c) Assam

[Solution Description]

The first oil well in India was successfully drilled in Assam in 1867. This marked the beginning of oil exploration and production in the country. Assam remains one of the key regions for oil extraction in India, along with Gujarat, Mumbai High, and the river basins of Godavari and Krishna.

Key Concept: Origin of Petroluem, Composition of Petroluem

c) Petroleum oil and natural gas are less dense than water.

[Solution Description]

Petroleum oil and natural gas are lighter than water due to their lower density. As a result, when petroleum is formed and trapped between rock layers, the oil and gas rise above the water layer because they are less dense. This natural separation occurs due to the differences in density among the substances involved.

Key Concept: Formation of Petroleum, Refining of Petroleum

a) Petroleum is formed from the remains of land animals.

[Solution Description]

Petroleum is formed from the remains of marine organisms that were buried under layers of sand and clay over millions of years. The absence of air, high temperature, and high pressure transformed these remains into petroleum and natural gas. During the refining process, petroleum is separated into various constituents such as petrol, diesel, kerosene, and lubricating oil. These constituents have different uses, such as fuel for vehicles, stoves, and lamps. The statement that is incorrect would be one that contradicts these well-established facts.

Key Concept: Formation of Petroleum, Density of Oil and Gas

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The formation of petroleum and natural gas involves the decomposition of marine organisms under high pressure and temperature over millions of years. As these substances are formed, they migrate through porous rock layers. Due to their lower density compared to water, petroleum and natural gas rise above the water layer and accumulate in reservoirs. This is why they are found above the water layer in underground deposits. Both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Formation of Petroleum

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description] The assertion states that petroleum is formed from organisms that lived in the sea, which is true according to the syllabus. The reason explains the process of how these organisms, after settling at the bottom of the sea, are transformed into petroleum under high temperature and pressure over millions of years. This explanation is also correct and directly supports the assertion. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Petroleum Formation

c) Sea

[Solution Description]

Petroleum is formed from organisms that lived in the sea. When these organisms died, their bodies settled at the bottom of the sea and were covered with layers of sand and clay. Over millions of years, under high pressure, high temperature, and in the absence of air, these organisms transformed into petroleum and natural gas.

Key Concept: Petroleum Formation and Deposits

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that petroleum is found above the water layer in underground deposits, which is true because oil and gas naturally float on water due to their lower density. The reason given is that oil and gas are lighter than water and do not mix with it, which is also true. Additionally, the reason correctly explains why petroleum is found above the water layer. Therefore, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Major Petroleum Reserves in India, Oil Exploration History

c) 1867 in Assam

[Solution Description]

The first oil discovery in India was made in 1867. This discovery took place in the Makum region of Assam. Therefore, the correct answer is 1867 in Assam.

Key Concept: Major Petroleum Reserves in India, Geographical Distribution

c) Rajasthan

[Solution Description]

The major petroleum reserves in India are found in Assam, Gujarat, Mumbai High, and the river basins of Godavari and Krishna. Rajasthan does not have significant petroleum reserves. Therefore, the correct answer is Rajasthan.

Key Concept: Refining of Petroleum, Petrochemicals

c) Assertion is true, but Reason is false.

[Solution Description]

The Assertion states that refining petroleum is essential to obtain petrochemicals used in various industries. This is true because refining separates various constituents of petroleum, and these constituents are further processed to produce petrochemicals like detergents, fibres, and plastics. The Reason claims that petrochemicals are derived directly from crude petroleum without refining, which is false. Petrochemicals are not obtained directly from crude petroleum; they are produced from refined products like natural gas or specific fractions obtained through refining. Therefore, the Assertion is true, but the Reason is false.

Key Concept: Refining of Petroleum, Uses of Petroleum Constituents

a) Fractional distillation

[Solution Description]

Paraffin wax has a high melting point and is a solid at room temperature. The most suitable process for separating it from crude oil is fractional distillation followed by cooling and solidification. Fractional distillation separates the crude oil into fractions based on boiling points, and paraffin wax solidifies upon cooling.

Key Concept: Refining Process

b) To separate its various constituents

[Solution Description]

Refining is the process of separating the various constituents or fractions of petroleum. This process is carried out in a petroleum refinery to obtain useful products like petrol, diesel, kerosene, etc.

Key Concept: Refining of Petroleum

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

Petroleum is a mixture of various constituents like petrol, diesel, kerosene, and lubricating oil. These constituents have different boiling points. During refining, petroleum is heated in a fractionating column, and each constituent is separated at its specific boiling point. This process is called fractional distillation. Therefore, the assertion that refining involves separating constituents based on boiling points is true. The reason given also correctly explains the assertion since the separation occurs due to differences in boiling points.

Key Concept: Constituents of Petroleum and Their Uses

c) Paraffin wax

[Solution Description]

From Table 3.1, paraffin wax is used in the manufacture of candles and ointments. Thus, the correct answer is paraffin wax.

Key Concept: Constituents of Petroleum and Their Uses

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that diesel is used as a fuel for heavy motor vehicles and electric generators, which is true according to the syllabus. The reason states that diesel is a constituent of petroleum obtained through the refining process, which is also true. Additionally, the reason correctly explains why diesel can be used as a fuel for heavy motor vehicles and electric generators, as it is a mixture of various constituents of petroleum separated during the refining process.

Key Concept: LPG Fuel Usage

b) Fuel for cooking

[Solution Description]

LPG is widely used as a fuel for cooking and heating in households. It is a clean and efficient source of energy, making it suitable for domestic use.

Key Concept: Uses of LPG

d) Fuel for home and industry

[Solution Description]

According to Table 3.1, the primary use of Liquefied Petroleum Gas (LPG) is as a fuel for home and industry.

Key Concept: Uses of Petroleum Constituents

b) Fuel for stoves

[Solution Description]

Kerosene is used as fuel for stoves, lamps, and jet aircrafts. It is not used as motor fuel for cars or heavy vehicles, nor is it used for lubrication.

Key Concept: Petroleum and its Uses

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that petrol is used as a fuel for light vehicles such as cars and bikes, which is true according to the syllabus. The reason explains that petrol is obtained from petroleum, which is also true. Moreover, the process of refining petroleum separates it into various constituents, one of which is petrol. Therefore, the reason correctly explains the assertion.

Key Concept: Constituents of Petroleum

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description] The syllabus clearly states that kerosene is a constituent of petroleum and is used as fuel for stoves, lamps, and jet aircrafts. Both the Assertion and Reason are true. Additionally, the Reason correctly explains why kerosene is used for these purposes, as it highlights its properties derived from being a petroleum product.

Key Concept: Refining, Kerosene Uses

c) Kerosene's moderate volatility and energy density make it suitable for multiple uses.

[Solution Description]

Kerosene has a moderate boiling point, making it less volatile than gasoline but more volatile than diesel. This property allows it to burn efficiently in stoves and lamps without being too explosive or too slow to ignite. Additionally, its energy density makes it suitable for jet engines, which require high energy output. Thus, kerosene's physical properties make it ideal for these applications.

Key Concept: Refining Process

c) Refining

[Solution Description] The process of separating the various constituents or fractions of petroleum is known as refining. This is carried out in a petroleum refinery, as mentioned in the syllabus.

Key Concept: Diesel: Used for heavy vehicles and generators

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The Assertion states that diesel is used as a fuel for heavy motor vehicles and electric generators. This is true as per the syllabus, which mentions that diesel is a fuel for such applications. The Reason states that diesel is a constituent of petroleum obtained through refining. This is also true as diesel is indeed one of the constituents of petroleum that is separated during the refining process. The Reason correctly explains why diesel can be used as fuel, as it is produced from petroleum refining. Therefore, both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Key Concept: Lubricating Oil

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that lubricating oil is used to reduce friction in machines, which is true as it is one of its primary uses. The reason explains how lubricating oil achieves this by forming a thin layer between moving parts, preventing direct contact and thereby reducing friction. Both the assertion and the reason are true, and the reason correctly explains the assertion.

Key Concept: Petroleum Refining

b) Refining

[Solution Description]

The process of separating the various constituents or fractions of petroleum is known as refining. This process is carried out in a petroleum refinery, as mentioned in the syllabus.

Key Concept: Uses of Paraffin Wax

c) Candles

[Solution Description]

Paraffin wax is used in making candles, ointments, and vaseline. This is explicitly stated in Table 3.1 of the syllabus.

Key Concept: Paraffin Wax Uses

c) Manufacturing of candles

[Solution Description]

Paraffin wax is a constituent of petroleum and is widely used in making ointments, candles, and vaseline. It is not typically used as a fuel or lubricant. Therefore, the correct use of paraffin wax is in the production of candles.

Key Concept: Bitumen Applications, Petroleum Constituents

b) Electrical insulation

[Solution Description]

Bitumen is widely used in road surfacing, waterproofing, and as a binding agent in roofing materials. However, it is not typically used as a primary material in electrical insulation, which requires materials with different properties such as high resistivity and thermal stability.

Key Concept: Bitumen vs. Coal-Tar, Environmental Impact

b) Reduced harmful emissions

[Solution Description]

One significant environmental benefit of using bitumen instead of coal-tar for road surfacing is the reduction in harmful emissions. Coal-tar contains polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic and can pollute the air and water. Bitumen, being a petroleum product, has lower levels of PAHs, making it a safer alternative for both human health and the environment.

Key Concept: Natural Gas, CNG, Pipelines

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that natural gas is transported through pipelines because it is easier and more economical compared to other transport methods. This is true as pipelines allow for continuous and efficient transport of natural gas over long distances without the need for frequent handling or storage. The reason states that the use of pipelines for natural gas transportation reduces the risk of environmental pollution and accidents associated with other transport methods. This is also true because pipelines minimize leakage and are generally safer than transporting gas via trucks or ships. Moreover, the reason correctly explains the assertion since the environmental and safety benefits of pipelines contribute to their ease and economic viability. Therefore, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Natural Gas Uses

d) All of the above

[Solution Description]

Natural gas is used for multiple purposes in India, including power generation, as a fuel for transport vehicles, and as a starting material for the manufacture of chemicals and fertilisers. It is also used directly for burning in homes and factories.

Key Concept: Natural Gas, CNG, Environmental Impact

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that CNG is a cleaner fuel compared to traditional fossil fuels like coal and petrol. This is true because CNG emits lower levels of harmful pollutants such as carbon monoxide, nitrogen oxides, and particulate matter. Moreover, it produces less carbon dioxide per unit of energy released, making it a more environmentally friendly option. The reason provided explains that CNG produces fewer pollutants and greenhouse gases when burned, which directly supports the assertion by providing the scientific basis for why CNG is considered a cleaner fuel. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Uses of Natural Gas, CNG

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that CNG is widely used as a fuel for transport vehicles due to its lower pollution levels compared to traditional fuels like diesel and petrol. This is true because CNG burns more cleanly, emitting fewer pollutants such as carbon monoxide, hydrocarbons, and nitrogen oxides. The reason provided is that CNG combustion produces fewer greenhouse gases and particulate matter, which is also true. Moreover, the reason correctly explains why CNG is considered a cleaner fuel and why it is preferred for transport vehicles. Therefore, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Key Concept: Assertion-Reason

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

Natural gas is indeed stored under high pressure as compressed natural gas (CNG) to make it easier to transport through pipelines and use in various applications, including power generation and as a fuel in industries. The reason provided states that CNG can be directly supplied through pipelines for burning in homes and factories, which is true and is one of the advantages of CNG. However, the reason does not directly explain why natural gas is stored under high pressure as CNG. Storing natural gas under high pressure as CNG is primarily done to reduce its volume for transportation, not just for direct supply through pipelines. Therefore, while both the assertion and the reason are true, the reason does not correctly explain the assertion.

Key Concept: Natural Gas as a Raw Material

b) Manufacturing of fertilisers

[Solution Description]

Natural gas is widely used as a starting material for the manufacture of chemicals and fertilisers. This is one of its primary applications in the industry.

Key Concept: Natural Gas Reserves in India

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description]

The assertion states that natural gas reserves in India are located in specific regions such as Tripura, Rajasthan, Maharashtra, and the Krishna Godavari delta. This is true as per the syllabus. The reason provided is that India has vast natural gas reserves due to the presence of sedimentary basins. While it is true that India has vast natural gas reserves, the reason does not directly explain why these reserves are specifically located in the mentioned regions. Therefore, both statements are true, but the reason does not correctly explain the assertion.

Key Concept: Conservation of Fossil Fuels, PCRA Tips

c) Rapid acceleration to reach higher speeds quickly

[Solution Description]

PCRA recommends driving at a constant speed, switching off the engine at traffic lights, maintaining correct tyre pressure, and regular vehicle maintenance. Rapid acceleration consumes more fuel, hence it is not recommended.

Key Concept: Classification of Natural Resources, Sustainability

c) Implementing practices that reduce consumption and enhance efficiency.

[Solution Description]

To ensure the sustainability of exhaustible resources like coal and petroleum, it is crucial to focus on conservation efforts such as reducing usage, enhancing efficiency, and exploring alternative energy sources. This approach helps in prolonging the availability of these resources and mitigating environmental impacts associated with their use.

Key Concept: Exhaustibility of Fossil Fuels

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

Fossil fuels like coal and petroleum are formed from the remains of dead organisms over millions of years under specific natural conditions. This process is extremely slow and cannot be artificially replicated in a laboratory. Therefore, the assertion that fossil fuels are exhaustible is true because their formation rate is far slower than their consumption rate. The reason provided also correctly explains why fossil fuels are exhaustible, as their formation process is naturally slow and not replicable in a lab. Hence, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Global Warming

c) Global warming.

[Solution Description]

The excessive use of fossil fuels leads to the release of large quantities of greenhouse gases such as carbon dioxide (\$CO_2\$) into the atmosphere. These gases trap heat from the sun, causing the Earth's temperature to rise, a phenomenon known as global warming. Global warming has several adverse effects, including melting polar ice caps, rising sea levels, and extreme weather events. Therefore, one major consequence of excessive use of fossil fuels is global warming.

Key Concept: Global Warming and Fossil Fuels

c) By releasing carbon dioxide which traps heat

[Solution Description]

Burning fossil fuels releases large amounts of carbon dioxide (CO$_2$) into the atmosphere. This greenhouse gas traps heat, leading to an increase in Earth's temperature, which is a major cause of global warming.

Key Concept: Fossil Fuels and Global Warming

c) It releases greenhouse gases that trap heat

[Solution Description]

Burning fossil fuels releases carbon dioxide ($CO_2$) and other greenhouse gases into the atmosphere. These gases trap heat from the sun, causing the Earth\'s temperature to rise, which is known as global warming.

Key Concept: Conservation of Fossil Fuels, Exhaustibility of Natural Resources

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description]

The assertion states that the conservation of fossil fuels is essential because their known reserves will last only a few hundred years. This is true as fossil fuels like coal, petroleum, and natural gas are exhaustible resources with limited reserves. The reason explains that fossil fuels are formed from the dead remains of living organisms over millions of years and cannot be replenished quickly. This is also true and directly explains why the conservation of these fuels is necessary. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Fossil Fuels and Conservation

c) Coal

[Solution Description]

Fossil fuels are natural resources formed from the remains of ancient organisms over millions of years. Examples include coal, petroleum, and natural gas.

Key Concept: Exhaustible Resources, PCRA Guidelines

b) 10 liters

[Solution Description]

To calculate the petrol saved, first determine the total consumption at varying speeds and at constant speed. At varying speeds, the car consumes 12 liters per 100 km. For 500 km, this would be $12 \times 5 = 60$ liters. At a constant speed, the car consumes 10 liters per 100 km. For 500 km, this would be $10 \times 5 = 50$ liters. The petrol saved is the difference between these two values: $60 - 50 = 10$ liters.