Q1. What is the simplest hydrocarbon?
a) Methane
b) Ethane
c) Propane
d) Butane
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Correct Answer: a) Methane
Explanation: Methane is the simplest hydrocarbon, consisting of a single carbon atom bonded to four hydrogen atoms. Its chemical formula is CH4. Methane is a major component of natural gas and is produced through various biological and geological processes, including anaerobic decomposition of organic matter. It is used as a fuel for heating, cooking, and electricity generation. Methane is also a potent greenhouse gas, contributing to climate change when released into the atmosphere.
Q2. Which type of hydrocarbon contains only single bonds between carbon atoms?
a) Alkanes
b) Alkenes
c) Alkynes
d) Aromatic hydrocarbons
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Correct Answer: a) Alkanes
Explanation: Alkanes are a type of hydrocarbon that contains only single bonds between carbon atoms. They have the general formula CnH2n+2. Alkanes are saturated hydrocarbons, meaning they have the maximum number of hydrogen atoms bonded to each carbon atom. They are relatively stable and are commonly found in petroleum and natural gas. Alkanes are used as fuels, lubricants, and starting materials for the synthesis of various organic compounds.
Q3. Which type of hydrocarbon contains at least one carbon-carbon double bond?
a) Alkanes
b) Alkenes
c) Alkynes
d) Aromatic hydrocarbons
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Correct Answer: b) Alkenes
Explanation: Alkenes are a type of hydrocarbon that contains at least one carbon-carbon double bond. They have the general formula CnH2n. Alkenes are unsaturated hydrocarbons, meaning they have fewer hydrogen atoms compared to alkanes due to the presence of double bonds. Alkenes are used in the production of plastics, solvents, and various organic compounds through processes such as polymerization and addition reactions.
Q4. Which hydrocarbon series is characterized by at least one carbon-carbon triple bond?
a) Alkanes
b) Alkenes
c) Alkynes
d) Aromatic hydrocarbons
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Correct Answer: c) Alkynes
Explanation: Alkynes are a type of hydrocarbon that contains at least one carbon-carbon triple bond. They have the general formula CnH2n-2. Alkynes are unsaturated hydrocarbons, similar to alkenes, but with triple bonds instead of double bonds. They are less common than alkenes and alkanes but have various industrial applications, including in organic synthesis and as starting materials for the production of polymers and pharmaceuticals.
Q5. Which hydrocarbon series is characterized by a ring structure with alternating single and double bonds?
a) Alkanes
b) Alkenes
c) Alkynes
d) Aromatic hydrocarbons
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Correct Answer: d) Aromatic hydrocarbons
Explanation: Aromatic hydrocarbons are characterized by a ring structure with alternating single and double bonds, known as an aromatic ring or benzene ring. The simplest aromatic hydrocarbon is benzene (C6H6). Aromatic hydrocarbons exhibit unique stability and reactivity due to resonance structures within the ring. They are widely used in the production of plastics, dyes, solvents, and pharmaceuticals, making them essential compounds in various industries.
Q6. Which hydrocarbon type is commonly found in rubber and latex?
a) Alkanes
b) Alkenes
c) Alkynes
d) Aromatic hydrocarbons
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Correct Answer: b) Alkenes
Explanation: Alkenes are commonly found in rubber and latex. Natural rubber, a polymer of isoprene (2-methyl-1,3-butadiene), is one of the most well-known examples of a substance containing alkenes. Isoprene is a diene, meaning it contains two carbon-carbon double bonds. Through polymerization, isoprene molecules link together to form long chains, resulting in the elastic properties of rubber. Synthetic rubber, produced from petroleum-derived alkenes, is also widely used in various applications.
Q7. Which hydrocarbon type is primarily used as a solvent in paints, varnishes, and adhesives?
a) Alkanes
b) Alkenes
c) Alkynes
d) Aromatic hydrocarbons
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Correct Answer: d) Aromatic hydrocarbons
Explanation: Aromatic hydrocarbons, such as benzene, toluene, and xylene, are primarily used as solvents in paints, varnishes, and adhesives. These compounds have excellent solvent properties, enabling them to dissolve a wide range of substances, including resins, pigments, and polymers. However, aromatic hydrocarbons pose health and environmental risks due to their toxicity and potential carcinogenicity, leading to regulations on their use and handling.
Q8. Which hydrocarbon type is commonly used as fuel for automobiles?
a) Alkanes
b) Alkenes
c) Alkynes
d) Aromatic hydrocarbons
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Correct Answer: a) Alkanes
Explanation: Alkanes, particularly hydrocarbons with straight-chain or branched structures, are commonly used as fuel for automobiles. Gasoline, diesel fuel, and aviation fuel primarily consist of alkanes derived from petroleum refining processes. When combusted, alkanes release energy in the form of heat, which is harnessed to power internal combustion engines. The combustion of alkanes produces carbon dioxide, water vapor, and other combustion products, contributing to air pollution and climate change.
Q9. Which hydrocarbon type is the main component of natural gas?
a) Alkanes
b) Alkenes
c) Alkynes
d) Aromatic hydrocarbons
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Correct Answer: a) Alkanes
Explanation: Alkanes, particularly methane (CH4), are the main components of natural gas. Natural gas is a fossil fuel formed from the decay of organic matter over millions of years. It primarily consists of methane, along with small amounts of ethane, propane, and other hydrocarbons. Natural gas is used as a fuel for heating, cooking, electricity generation, and industrial processes due to its relatively clean combustion and high energy content.
Q10. Which hydrocarbon type is commonly used as a refrigerant and propellant in aerosol sprays?
a) Alkanes
b) Alkenes
c) Alkynes
d) Aromatic hydrocarbons
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Correct Answer: b) Alkenes
Explanation: Alkenes, such as ethylene (C2H4) and propylene (C3H6), are commonly used as refrigerants and propellants in aerosol sprays. These compounds exhibit low boiling points and vapor pressures, making them suitable for applications requiring rapid vaporization and cooling. Alkenes are also used as starting materials in the production of plastics, detergents, and various organic compounds, highlighting their versatility in industrial processes.