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 manmade materials synthetic rubber rubber polymer

In the process of vulcanization:

  1. natural rubber is heated with sulphur

  2. natural rubber is heated with carbon

  3. natural rubber is heated with phosphorous

  4. natural rubber is heated with sodium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Vulcanization is a chemical process by which the physical properties of natural or synthetic rubber are improved. In its simplest form, vulcanization is brought about by heating rubber with sulfur.

Multiple choice physics friction increasing and reducing friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it

The substance that helps to ______ friction are called lubricants.

  1. increase

  2. decrease

  3. create

  4. eliminate
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Oils, grease, graphite, etc., are examples of lubricants. These form a thin layer between the two surfaces in contact thus avoiding them from scrubbing directly against each other. This makes the movement smooth and reduces friction.

Multiple choice chemistry chemical thermodynamics calorific value occurrence of carbon compounds in nature study of enthalpy

Gross and net calorific value of fuel will be the same :

  1. if its ash content is zero

  2. under no circumstances

  3. if its carbon content is very low

  4. if its hydrogen/hydrogen compound content is zero
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The gross or high heating value is the amount of heat produced by the complete combustion of a unit quantity of fuel. 


The net, or lower, value is determined by calculation and equals the gross calorific value minus the latent heat of the water vapor formed from the combustion of hydrogen and from any moisture present in the fuel. 

Gross and net calorific value of a fuel will be the same if its hydrogen compound content is zero.

Hence, option $D$ is correct.

Multiple choice chemistry chemical thermodynamics calorific value occurrence of carbon compounds in nature study of enthalpy

Presence of __________ in a dry gaseous fuel does not contribute to its calorific value.

  1. sulphur

  2. oxygen

  3. hydrogen

  4. carbon
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The energy contained in a fuel or food, determined by measuring the heat produced by the complete combustion of a specified quantity of it. This is now usually expressed in joules per kilogram. Oxygen present in dry gaseous fuel does not contribute to its calorific value.

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

Junker's calorimeter is used to determine the calorific value of ___________.

  1. pulverised coal

  2. gaseous fuels

  3. fuel oil

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Calorimeter is the instrument used to measure calorific value of heat produced by combustible substances. Junker's calorimeter is used to determine the calorific value of gaseous fuels.

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

Which of the following gaseous fuels has the lowest calorific value?

  1. Gober gas

  2. Refinery gas

  3. Converter gas

  4. Blast furnace gas
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Calorific value of these gases are listed in table
Gober gas $= $  $5kWh/Nm^3$
refinery gas $= $ $1.5kWh/Nm^3$
Converte gas$ = $ $3kWh/Nm^3$
Blast furnace gas $=$  $0.9kWh/Nm^3$

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

Gross & net calorific value is the same for ___________.

  1. blast furnace gas

  2. coke oven gas

  3. L.D. converter gas

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gross & net calorific value is the same for L.D converter gas. Calorific value is the total quantity of heat liberated by the complete combustion of a unit mass of the fuel in air or oxygen. It is expressed in $kcal/m^3$ or British thermal unit (B.T.U) per cubic foot.

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

Which among the following is the best fuel?

  1. Wood with calorific value 4000 Cal/g

  2. Coke with calorific value 8000 Cal/g

  3. Coal with calorific value 7000 Cal/g

  4. Kerosene with calorific value 11,200 Cal/g
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Higher the heating value or higher the calorific value better the fuel is, so kerosene has a higher heating value which is measured by bomb calorimeter.

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

The heat produced by burning 1 g of fuel completely is known as _____________.

  1. heat capacity

  2. calorific value

  3. vapour density

  4. boiling point
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 Calorific value is the quantity of heat produced by the complete combustion of a given mass of a fuel, usually expressed in joules per kilogram. It can be defined as the amount of heat energy produced on complete combustion of 1 Kg of fuel.


Hence, the correct option is $\text{B}$

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

The calorific values of wood, bituminous coal, natural gas and charcoal vary in the order:

  1. wood > bituminous > natural gas > charcoal

  2. wood > bituminous coal > charcoal > natural gas

  3. natural gas > charcoal > bituminous coal > wood

  4. natural gas> bituminous coal> wood> charcoal
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Natural gas         $ = 43000 kJ/kg$

Charcoal             $ = 29600 kJ/kg$
Bituminous coal $ = 23250 kJ/kg$
Wood                   $  =  17400 kJ/kg$

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

Which one of the following has the highest calorific value?

  1. Kerosene

  2. Biogas

  3. LPG

  4. Petrol
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The calorific value of a fuel is the quantity of heat produced by its combustion - at constant pressure and under a conditions known as " normal " of temperature and pressure (i.e. to 0oC and under a pressure of 1,013 mbar). 
The combustion of a fuel product generates water vapor. Certain techniques are used to recover the quantity of heat contained in this water vapor by condensing it. 
The Higher Calorific Value (or Gross Calorific Value - GCV) supposes that the water of combustion is entirely condensed and that the heat contained in the water vapor is recovered. 
The Lower Calorific Value (or Net Calorific Value - NCV) supposes that the products of combustion contains the water vapor. The heat contained in the water vapor is not recovered. 
LPG has a typical specific calorific value of 46.1 MJ/kg.
Calorific value of Bio gas is about 19 to 25 MJ/cubic meter, depending on the methane percentage in the biogas mix.
Heat of combustion of kerosene for lower heating value is 43.1 MJ/kg, and for higher heating value is 46.2 MJ/kg.
Petrol, calorific value of which is 45.8 MJ/kg.
Thus, LPG has highest calorific value among above.