Petroleum and natural gas - class-VIII

During carbonisation an organic substance converts into carbon or a carbon-containing residue through pyrolysis or destructive distillation. 

Substances which contain organic matter can undergo carbonization. Minerals do not contain any organic matter and cannot undergo carbonization.

The process of breaking higher hydrocarbons with high boiling points into a variety of lower hydrocarbons that are more volatile (low boiling), is called cracking (or pyrolysis). For example, a higher hydrocarbon $C _{10}H _{22}$ splits according to the reaction.

$C _{10}H _{22}  \xrightarrow {heat \ 770K} C _8H _{18} + C _2H _4$
The process of cracking or pyrolysis increases the relative amounts of the lower hydrocarbons, which exists in a gaseous state, while higher hydrocarbons exist in the liquid or solid state.

Process of conversion of wood into coal by biochemical process over a millions of years is called carbonation.This process occurs in the deep level of earth.

Hence option B is correct.

Cracking is a chemical process in petroleum refining where heavy hydrocarbon molecules of high molecular mass are broken down into lighter, more useful molecules of lower molecular mass.

Octane number is used to grade gasoline (petrol) based on its anti-knock properties. Diesel oil is graded using the cetane number.

Branched-chain hydrocarbons generally have higher octane numbers than straight-chain hydrocarbons because they burn more smoothly in engines.

All the three reactions, i.e. alkylation, cyclisation, and isomerisation convert straight-chain hydrocarbons to branched-chain or cyclic compounds, which changes the percentage of straight-chain hydrocarbon. 

Various fractions obtained during the fractional distillation of petroleum can be categorized into two viz, Petroleum products used as fuels: Petroleum gas, petrol, kerosene, diesel, fuel oil; Petroleum product not used as fuel:- Petroleum ether, greases, petroleum jelly, paraffin wax, pitch, asphalt.

Cracking is defined as “the decomposition of high boiling hydrocarbons of high molecular weight into smaller low boiling hydrocarbons of low molecular weight”. Usually high boiling point hydrocarbons are liquids and low boiling point hydrocarbons are gases.

Carbonization of dead plants and animals does not happen in the presence of oxygen. This is the procedure which takes place inside the earth crust under high pressure and temperature.

Carbonization is the term which means destructive distillation of coal which is done in the absence air in order to obtain coke and other fractions having greater percentage of carbon than the original material.

A good quality coke is generally made from carbonisation of good quality coking coals.

Any of the following method is used for cracking
(A) Vapour phase cracking
(B) Liquid phase cracking
(C) Cracking in presence of hydrogen.

Cracking converts high molecular weight (less valuable) fractions into lower molecular weight (more valuable) fractions, such as gasoline. The statement claims the opposite.

Reforming (also called aromatization) is the conversion of aliphatic hydrocarbons into aromatic hydrocarbons containing the same number of carbon atoms.

All of the given statements are true.
(A) Gasolines with octane number of 74 are called regular gasolines.
(B) Gasolines with octane number lower than 74 are called third grade gasolines.
(C) Gasolines with octane number of 84 or above are called premium gasolines.

Ordinary gasolines having an octane number of 74 are used in motor cars, scooter and motorcycles.

Octane number expresses the knocking characteristics of petrol. n-heptane (a constituent of petrol) knocks very badly, so its anti-knock value has been given zero. On the other hand, iso-octane (also a constituent of petrol) gives very little knocking, so its anti-knock value has been given 100
The higher the octane number, the more compression the fuel can withstand before detonating (igniting) i.e fuels with a higher octane rating are used in high-performance gasoline engines that require higher compression ratios and with lower octane numbers are ideal for diesel engines,as diesel engines do not compress the fuel, but rather compress only air and then inject fuel into the air which was heated by compression.

A motor fuel is said to have an octane number of 80 when it is as good as a mixture of 20% n-heptane and 80% of iso-octane.
The octane number of gasoline is defined as the percentage of iso-octane present in a mixture of iso-octane and n-heptane, when the mixture has the same knocking in the engine, as the gasoline under examination.

The octane number of gasoline is defined as the percentage of iso-octane present in a mixture of iso-octane and n-heptane, when the mixture has the same knocking in the engine, as the gasoline under examination.

The hydrocarbon iso-octane which has good resistance to knocking even in highest compression motors is arbitrarily given an octane number of 100. Whereas n-heptane which knocks the maximum is arbitrarily given the value of 0.

Cetane number is the percentage of cetane (hexa-decane) in a given diesel sample.

Ferric oxide is used as a catalyst in the manufacture of synthetic petrol by Bergius method.

Octane number can be increased by any of the following methods:
(1) Increasing the percentage of branched or cycloalkanes.
(2) By addition of BTX or TEL.
(3) By addition of powder alcohol (ethanol).

Octane number is the percentage by volume of iso-octane present in a mixture of iso-octane and heptane which has the same knocking performance as the sample fuel. For eg - octane number of triptane is 125. Hence, the answer is D.

Cyclic alkanes have relatively higher value of octane number.

Aviation gasoline has octane number of 100 or more. Aviation gasoline is the fuel used in aeroplanes. Use of gasoline with lower octane number may lead to the problem of engine knocking.

In case of straight chain hydrocarbons, the octane number decreases with increase in the length of the chain.

The octane numbers of aromatic hydrocarbons are exceptionally high.

Introduction of double or triple bond increases the value of octane number.

$n$-nonane has an octane number of $-20$.

Compounds with more than 100 and less than 0 octane numbers are  also known. For example triptane has octane number of 125 and n -nonane has octane number of -45.

Branching of chain increases the value of octane number.

Cracking, alkylation and isomerization will increase the octane number of gasolines.

The addition of benzene, toluene and xylene will increase the octane number of gasoline.

During carbonization or destructive distillation of coal, bituminous coal is heated in iron or fireclay retorts to high temperature (1000-1400 deg C) in absence of air.

In propagation step of cracking process, a free radical removes a hydrogen atom from another molecule, turning the second molecule into a free radical.

In steam cracking, initiation usually involves breaking a chemical bond between two carbon atoms, rather than the bond between a carbon and a hydrogen atom.

In cracking, the initial process involves the breaking down of hydrocarbons into free radicals.Only a small fraction of the feed molecules actually undergo initiation, but these reactions are necessary to produce the free radicals that drive the rest of the reactions.

An unsaturated compound has a higher octane rating than a saturated compound.

Common methods for manufacturing Synthetic fuels include the Fischer Tropsch conversion, methanol to gasoline conversion or direct coal liquefaction.

Octane number $\propto$ 1/knocking tendency

The major products from hydrocracking are jet fuel and diesel, but low sulphur naphtha fractions and LPG are also produced. All these products have a very low content of sulphur and other contaminants.

Octane number is a standard measure of the performance of an engine or aviation fuel. The higher the octane number a fuel has, more compression the fuel can withstand before igniting. Also, higher the octane number, better is the performance of the fuel.
In the given options, toluene has the highest octane number.

• Oxygenates are the chemical compounds containing oxygen.
  
• They are usually employed as gasoline additives.
• Commonly used oxygenates are alcohols or ethers.
• Here, ethanal, MTBE and TAME are ethers. Thus, MEG (Mono ethylene glycol) is not used as oxygenates.   

Crude oil in the raw form is obtained by drilling from the earth's crust. It has to be refined in order to convert it to useful products such as petrol, kerosene, diesel etc. The industrial plant where the refining of crude oil is done is called  an oil refinery. 

In the refinery for lubricating oil, solvent refining, clay treatment and hydrotreatment are the important processes. The solvent used for refining purpose has to be pure. Clay treatment is done to remove colour, odour and sulphur from the oil. 

Cleveland is an open cup apparatus is also known as open cup tester. In this, the cup is first filled with the product to a certain level. Then the temperature is raised rapidly and then at a slow constant rate as it approaches the theoretical flashpoint. The lowest temperature at which a small test flame passing over the liquid ignites the vapour is considered chemical's flashpoint.

Hydrocarbon is a compound containing carbon atoms and hydrogen atoms. Methane is the hydrocarbon found in the earth's crust. It is the simplest hydrocarbon. It is mainly used as fuel.

Propylene is often referred to as the crown prince of petrochemicals. Propylene is a byproduct of steam crackers and the varying amount of olefins is produced from steam crackers depending on the type of feedstock. Other sources of propylene may be the recovery of propylene from FCC light ends, Propane dehydrogenation and fluidized bed catalytic cracking.

Bharat stage emission standard is an emission standard institute which is governed by the government of India to regulate the air pollutants from internal combustion engines or vehicle motors.Bharat Stage III norms or Euro III norms were enforced in October 2010 all over the country. According to this benzene content in gasoline should be 1%.

Aniline point is the lowest temperature at which equal volumes of fresh aniline and an oil are completely miscible. Higher the aniline point, higher is the diesel index. Diesel index indicates the ignition quality of the fuel. 

In petroleum chemistry, Steam cracker plant is a process by which complex organic molecules are broken down to the simpler molecules using steam. Here, the cracking is done by using steam. Ethane cracking consumes the maximum amount of steam.

In catalytic reforming process, high octane number reformate is formed which is the main component of the motor, fuel, aviation gasoline or aromatic rich feedstock. Favourable Conditions for the reaction are High temperature, Low pressure and low space velocity.

Octane number can be determined by RON, MON and AKI. The most common
method used for the measurement is RON. RON is determined by running the
fuel in a test engine and comparing the results with those for mixtures
of iso- octane and $n$- heptane. The RON/MON value for $n$- heptane is 0.

Octane number can be determined by all the three methods. The most common
method used for the measurement is RON. RON is determined by running the
fuel in a test engine and comparing the results with those for mixtures
of iso-octane and $n$-heptane.

Octane number can be determined by RON, MON and AKI. The most common
method used for the measurement is RON. AKI is the arithmetic mean of RON and MON. 

Higher is the octane number higher is the activation energies. Activation energy is the amount of energy required to initiate combustion. 

• The fuels with higher octane ratings will require high activation energies and are less prone to auto-ignition.
• They can withstand the greater rise in temperature during the compression stroke of an internal combustion engine without auto igniting and thus allow more power to be extracted.
• They have lower cetane number. Cetane number and octane rating are opposite to each other.
• A fuel with higher octane rating leads to less engine knocking.
  

Octane number can be determined by RON, MON and AKI. The most common method used for the measurement is RON. RON is determined by running the fuel in a test engine and comparing the results with those for mixtures of iso-octane and $n$- heptane. The RON/MON values of iso-octane is 100.

Octane number can be determined by RON, MON and AKI.The most common
method used for the measurement is RON. 

In catalytic reforming process, the noble metals platinum and rhenium are the catalysts used on a silica or silica-alumina support base. Fresh catalyst is chlorinated prior to use. On the other hand, an excessive chlorination could depress excessively the activity of the catalyst. Also in the case of the semi-regenerative catalytic reformer, the catalyst is reduced over time by carbonaceous coke deposition and chlorine loss.

In catalytic reforming process, high octane number reformate is formed which is the main component of the motor, fuel, aviation gasoline or aromatic rich feedstock. The noble metals platinum and rhenium are the catalysts used on a silica or silica-alumina support base. Fresh catalyst is chlorinated prior to use.

In catalytic reforming process; high octane number reformate is formed which is the main component of the motor, fuel, aviation gasoline or aromatic rich feedstock. The noble metals platinum and rhenium are the catalysts used on a silica or silica-alumina support base. Fresh catalyst is chlorinated prior to use.

Hydrogenolysis is a reaction where hydrogen is added to a compound and breaks that compound’s bonds, forming two molecules. This results in the formation of lighter hydrocarbons.

In catalytic reforming process, high octane number reformate is formed which is the main component of a motor, fuel, aviation gasoline or aromatic rich feedstock. The noble metals platinum and rhenium are the catalysts used for it.

Catalytic reforming is a chemical process that is used to convert petroleum refinery naphthas, typically those which are having lower octane ratings into high octane liquid products which are termed as reformates. They are the components of high octane gasoline.

1. Kerosene is obtained from petroleum between $ 200^0C  to  300^0C $.

Hydrocarbons present in

Petrol, which has octane number 80 contain 20% n-heptane and 80% iso-octane.

The process of separating the various constituents of petroleum is known as fractional distillation.

90-Octane petrol is the  mixture of 90% iso-octane and 10% normal (straight chain) heptane.

Hence option C is correct.

When coal is passed through hydrogen under heat and pressure it produces synthetic petrol and kerosene which is used for household fuel.

Octane rating or octane number is a standard measure of the performance of a motor- or aviation fuel. The higher the octane number, the more compression the fuel can withstand. fuels with a higher octane rating are used in high performance petrol engines that require higher compression ratios. thus it reflects the quality of fuel.

A cetane number is the measure of the quality of the diesel . Higher cetane number indicates that the fuel ignites more readily when sprayed over hot compressed air.

The following fuels are present in the heavy oil obtained during petroleum distillation 1. Gas oil  2.Fuel oil and Diesel oil.

So all the given options are correct.

Hence option D is correct.

Unisol process is a regenerative method for not only extracting or removing mercaptans but also some of the nitrogen compounds. In this process first gasoline is washed counter-currently with aqueous caustic methanol solution. The spent caustic is regenerated in a stripping tower where the methanol, water and mercaptans are extracted.