Chemistry · General Awareness

Carbon and Fossil Fuels

1,898 Questions

Review fundamental concepts regarding carbon compounds, coal distillation, and fossil fuel formation. This segment covers the chemical properties and industrial applications of natural gas and crude oil. Practicing these questions will strengthen your chemistry foundation for general science sections.

Coal distillationPetroleum formationProperties of crude oilNatural gas applications

Carbon and Fossil Fuels Questions

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

Unburnt carbon particles are present in the:

  1. Blue zone

  2. Dark inner zone

  3. Luminous zone

  4. Non-luminous zone
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The circular dark ring is formed on the slide is due to the deposition of unburnt carbon particles present (middle) in the luminous zone of the candle.
Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

Which of the following statement is NOT true?

  1. Flame can be seen over burning solids and liquids

  2. Type of flame depends upon the amount of oxygen available

  3. Invisible zone of a flame is the least hot zone

  4. Blue-zone indicates complete combustion of fuel
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Invisible-zone of the flame is also called as non-luminous zone which is the zone of complete combustion. Due to complete combustion the zone become hottest zone of the flame.

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

Type of flame produced by a fuel depends upon _________.

  1. calorific value

  2. amount of oxygen

  3. type of fuel and its chemical composition

  4. all of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Type of flame depends upon the amount of oxygen available for burning of the fuel. If oxygen is present in sufficient amount it is called as oxidizing flame but oxygen is not available in sufficient amount it is called as reducing flame.

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

A circular blackish ring on the glass plate kept over the candle flame indicates ___________.

  1. Complete combustion

  2. Dark zone of the flame

  3. Non-luminous zone

  4. Luminous zone
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A circular blackish ring on the glass plate kept over the candle flame indicates the luminous zone. The candle flame consists of mainly 3 zones depending on the temperature i.e the outer zone ( hottest among all, blue in colour, complete combustion occurs here and is the non-luminous part of the flame), middle zone ( moderately hot, yellow in colour, partial combution), inner zone (least hot and black in colour, and is the luminous part).

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

The blue zone in a LPG flame indicates _________.

  1. unburnt vapours

  2. partial decomposition

  3. moderately hot

  4. hottest and complete combustion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Flame color determines the rate of combustion and thus the temperature difference producing a different color flame. In LPG the blue zone is the zone of complete combustion of fuel. So, the amount of soot decreases and the temperature is highest as high heat is released.

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

Which is the hottest part of Bunsen flame?

  1. In the blue zone

  2. Just above the tip of the primary flame

  3. At the top of the outer core

  4. Just above the inner core
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The hottest part of a Bunsen flame is just above the tip of the primary (inner) blue cone, where complete combustion occurs.

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

Which of the following flames is produced by a candle?

  1. Blue flame

  2. Non-luminous flame

  3. Light giving flame

  4. Yellow luminous flame
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A candle flame is a luminous flame because the wax vapors do not burn completely, leaving glowing carbon particles that produce a yellow light.

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

The hottest part of a candle flame is the __________.

  1. luminous zone

  2. dark zone

  3. hot zone

  4. non-luminous zone
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The Non-Luminous zone is the region of the complete combustion. If you look at a candle flame closely. You will see an "aura" formed around the candle. Since this zone is complete combustion and it is the hottest part of the flame.
Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

Which is the hottest part in the flame of the candle?

  1. Blue

  2. Yellow

  3. Black

  4. Wax part
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The hottest part of a candle flame are actually the blue, almost invisible area near the base. Where oxygen is drawn in and blue or white part around the edge. In this area flame meets the oxygen-rich air all around it. The flame get progressively cooler as you move in from the outside edge toward the wick.

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

Colour of the flame is dependent on the ______________.

  1. supply of oxygen

  2. nature of fuel

  3. ignition temperature of the fuel

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The colour and temperature of a flame are dependent on the nature of the fuel involved in the combustion.

When excited, every element can emit light; the wavelength, and hence the colour, of the emitted light, is characteristic of each element. An example of this is the blue flame from gas ovens, which is due to the combustion of methane or liquified petroleum gas.

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

During burning of candle, different zones of combustion in the flame are listed below:-


a) Outermost zone
b) Innermost zone
c) Middle zone

The correct order of temperature of zones is :

  1. $A>B>C$
  2. $C>B>A$
  3. $B>C>A$
  4. $A>C>B$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The flame consist of three zones: 

  1. The outermost zone is the hottest among the 3 and is blue in colour.
  2. The middle zone is moderately hot and is yellow in colour.
  3. The innermost zone is the least hot and black in colour.