Q1. Which of the following is the primary constituent of petroleum?
a) Oxygen
b) Carbon
c) Nitrogen
d) Hydrogen
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Correct Answer: b) Carbon
Explanation: Petroleum is a complex mixture of hydrocarbons, which are compounds composed of carbon and hydrogen atoms. These hydrocarbons vary in structure and molecular weight, giving rise to different fractions of petroleum such as gasoline, diesel, and kerosene.
Q2. Which type of hydrocarbon molecules dominate the composition of paraffin wax obtained from petroleum?
a) Saturated hydrocarbons
b) Unsaturated hydrocarbons
c) Aromatic hydrocarbons
d) Aliphatic hydrocarbons
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Correct Answer: a) Saturated hydrocarbons
Explanation: Paraffin wax, a byproduct of petroleum refining, primarily consists of saturated hydrocarbons, also known as paraffins. These molecules have single bonds between carbon atoms, resulting in a straight-chain or branched structure and a high melting point, making them suitable for various industrial applications.
Q3. What is the main factor determining the properties of different fractions obtained during petroleum refining?
a) Molecular weight
b) Carbon content
c) Density
d) Boiling point
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Correct Answer: d) Boiling point
Explanation: The properties of different petroleum fractions, such as gasoline, diesel, and kerosene, are primarily determined by their boiling points. During petroleum refining, crude oil is separated into fractions based on their boiling points through a process called fractional distillation.
Q4. Which of the following petroleum fractions is commonly used as a fuel for jet engines?
a) Gasoline
b) Diesel
c) Kerosene
d) Lubricating oil
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Correct Answer: c) Kerosene
Explanation: Kerosene, also known as aviation fuel, is a petroleum fraction with a higher boiling point than gasoline and diesel. It is commonly used as a fuel for jet engines due to its suitable properties, including high energy content and low freezing point.
Q5. What is the primary method used for separating different fractions of petroleum during refining?
a) Fractional crystallization
b) Distillation
c) Extraction
d) Polymerization
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Correct Answer: b) Distillation
Explanation: Fractional distillation is the primary method used for separating different fractions of petroleum during refining. Crude oil is heated in a fractional distillation tower, and the vaporized hydrocarbons condense at different temperatures, allowing for the separation of fractions based on their boiling points.
Q6. Which of the following petroleum fractions has the highest octane rating and is commonly used as fuel for spark-ignition engines?
a) Diesel
b) Kerosene
c) Gasoline
d) Lubricating oil
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Correct Answer: c) Gasoline
Explanation: Gasoline, also known as petrol, is a petroleum fraction with a high octane rating, making it suitable for use as fuel in spark-ignition engines, such as those found in cars and motorcycles.
Q7. What is the main purpose of refining crude oil into various petroleum fractions?
a) To increase its viscosity
b) To reduce its volatility
c) To separate impurities
d) To obtain products with specific properties
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Correct Answer: d) To obtain products with specific properties
Explanation: The main purpose of petroleum refining is to separate crude oil into various fractions with specific properties suitable for different applications, such as transportation fuels, lubricants, and petrochemical feedstock.
Q8. Which of the following is a common method for upgrading heavy fractions of petroleum to lighter, more valuable products?
a) Hydrocracking
b) Isomerization
c) Alkylation
d) Polymerization
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Correct Answer: a) Hydrocracking
Explanation: Hydrocracking is a refining process that involves breaking down heavy hydrocarbon molecules into lighter fractions by reacting them with hydrogen gas at high temperatures and pressures. This process improves the quality and increases the yield of valuable products such as gasoline and diesel.
Q9. What is the primary purpose of adding additives to gasoline during refining?
a) To increase its energy content
b) To improve its color
c) To enhance its performance and reduce emissions
d) To decrease its volatility
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Correct Answer: c) To enhance its performance and reduce emissions
Explanation: Additives are added to gasoline during refining to improve its performance in terms of combustion efficiency, engine cleanliness, and emissions reduction. These additives can enhance fuel octane rating, reduce engine deposits, and minimize emissions of harmful pollutants.
Q10. Which of the following petroleum fractions is commonly used as a raw material for producing plastics, synthetic fibers, and rubber?
a) Gasoline
b) Diesel
c) Naphtha
d) Asphalt
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Correct Answer: c) Naphtha
Explanation: Naphtha is a light petroleum fraction with a boiling range between gasoline and kerosene. It is commonly used as a feedstock for petrochemical processes, including the production of plastics, synthetic fibres, and rubber.