Chemistry · General Awareness

Carbon and Fossil Fuels

1,756 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

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. 

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

If you watch a burning candle carefully, you will find different colurs in the flame. Which is the hottest part of the candle flame?

  1. The middle orange part

  2. The middle, yellow part

  3. The outermost portion that is blue

  4. The innermost black zone
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The outermost portion that is blue.

The hottest part of the candle flame is the blue part, at $1670^oF$ ($1400^oC$) i.e., the outermost portion, where the flame has the most oxygen and you are getting complete combustion.

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

The flame of the candle has three zones. The outer zone is blue, the middle zone is yellow and the inner zone is black. Which is correct regarding this?

  1. The outer zone is hottest hot.

  2. The middle zone is hottest

  3. The inner zone is least hot

  4. All the zones have same temperature
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

Candles produce light by releasing heat. A candle flame consists of three zones. Each zone has different temperatures and colors.

  • The first zone is called the Outer zone
  • The second zone is called the Middle zone
  • The third zone is called the Inner zone

The outer zone is blue in color, due to complete combustion,. This zone is the hottest zone.

The middle one is in yellow color, which is the bright part of the flame. It is moderately hot and partial combustion of fuel takes place.

The least hot region of the flame is innermost zone. This inner zone is black in color due to the presence of unburnt wax vapors.

Multiple choice solid waste and its management conservation of environment

 The rate of pyrolysis increases with 

  1. Temperature

  2. Pressure

  3. Preciptation

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Pyrolysis is the process of breaking organic compounds in the presence of heat but in absence of oxygen. The process accelerates with increase in temperature. 
So, the correct answer is 'Temperature'
Multiple choice evs how to save fuel fuels fuel and effects of burning fuel study of combustion

_____ is any material that can be made to react so that it releases chemical or nuclear energy as heat.

  1. Fossil fuel

  2. Fuel

  3. Oil

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

A fuel is any material that can be made to react so that it releases chemical or nuclear energy as heat or to be used for work. The heat energy released by reactions of fuels is converted into mechanical energy via a heat engine.

Multiple choice evs how to save fuel fuels fuel and effects of burning fuel study of combustion

What is an ideal fuel?

  1. It has high calorific value

  2. It is cheap

  3. It is readily combustible

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

An ideal fuel is cheap, readily available, easy to transport and readily combustible. It has high calorific value. It does not produce gases or residues that pollute environment.

Multiple choice evs how to save fuel fuels fuel and effects of burning fuel study of combustion

The ignition temperature of an ideal fuel should _____________.

  1. Lowest

  2. Highest

  3. Neither too high nor too low

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ideal fuel should have a proper ignition temperature, so that it can be burned easily. The ignition temperature of an ideal fuel should neither be too low nor too high. If the ignition temperature of the fuel is very low, then the fuel will catch fire too easily and hence it will be very unsafe to use it. On the other hand, if the ignition temperature is too high, then it will be very difficult to light the fuel.