Tag: fossil fuels

Questions Related to fossil fuels

The octane numbers of aromatic hydrocarbons are exceptionally low.

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. True

  2. False

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Correct Option: B
Explanation:

The octane numbers of aromatic hydrocarbons are exceptionally high.

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

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. True

  2. False

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Correct Option: B
Explanation:

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

What is the octane number of $n$-nonane?

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. 0

  2. $-20$

  3. 100

  4. more than 100

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Correct Option: B
Explanation:

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

Compounds with more than 100 and less than 0 octane numbers are not known.

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. True

  2. False

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Correct Option: B
Explanation:

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 decreases the value of octane number.

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. True

  2. False

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Correct Option: B
Explanation:

Branching of chain increases the value of octane number.

Which of the following will increase the octane number of gasolines?

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. cracking

  2. alkylation

  3. isomerisation

  4. all of the above

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Correct Option: D
Explanation:

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


 

The addition of which of the following will increase the octane number of gasoline?

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. benzene

  2. toluene

  3. xylene

  4. all of the above

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Correct Option: D
Explanation:

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

During carbonisation or destructive distillation of coal, bituminous coal is heated in iron or fire clay retorts to high temperature (500 deg C) in presence of air.

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. True

  2. False

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Correct Option: B
Explanation:

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 cracking, reaction is propagated through:

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. absorption of hydrogen by the formed radical

  2. release of hydrogen by the formed radical

  3. gain of electrons by the formed radical

  4. release of electron by formed radical

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Correct Option: A
Explanation:

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

Which one is true for the octane number of following organic compounds?

chemistry energy rocks and minerals petroleum and natural gas fossil fuels

  1. Aromatic Compound $>$ Aliphatic compound

  2. Aromatic compound $<$ Aliphatic compound

  3. Aromatic compound $=$ Aliphatic compound

  4. None of the above

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Correct Option: A
Explanation:
The octane number of a fuel is based on how fuels auto-ignite, under compression.
1. It is based on the scale where isooctane is 100 (minimal ignition under pressure) and heptane is 0 (easily ignites under pressure).
For example, petrol with an octane number of 92 has the same knock as a    mixture of 92% isooctane and 8% heptane.
2. Octane rating decreases with an increase in the carbon chain length.
3. Octane ratings increase with carbon chain branching.
4. Octane ratings increase in aromatics with the same number of carbons.

Hence, the correct option is $A$