These are Definitions of Chapter =>6
(Combustion & Flame) Of Class 8, Learn And Practice For CBSE Examinations.
Definitions:
1. Combustion=> A
chemical process in which a substance reacts with oxygen to give off heat is
called combustion.
2. Combustible=> The substance that undergoes combustion is said to be combustible.
3. Fuel=>
Combustible is also called a fuel. It may be solid, liquid or gas.
4. Flame=> A
hot glowing body of ignited gas that is generated by something on fire.
5. Charcoal=> A
porous black solid, consisting of an amorphous form of carbon, obtained as a
residue when wood, bone, or other organic matter is heated in the absence of
air.
6. Nuclear Reaction=>A process in which the structure and energy content of an atomic nucleus are changed by interaction with another nucleus or particle.
7. Ignition Temperature=> The lowest temperature at which a substance catches a fire is called
ignition temperature.
8. Combustible Substance=> Combustibility is a measure of how easily a substance will set
on fire, through fire or combustion. This is an important property to consider
when a substance is used
for construction or is being stored. It is also important in processes that
produce combustible substances as a by-product.
9. Inflammable Substance=> The substances which have very low ignition temperature and can easily
catch fire with a flame are called inflammable substance. Examples of
inflammable substance are petrol, alcohol, liquified petroleum gas (LPG) etc.
10. Fire Extinguisher=> A portable device that discharges a jet of water, foam, gas,
or other material to extinguish a fire.
11. Rapid Combustion =>The gas burns rapidly and produces heat and light. Such combustion is
known as rapid combustion.
1 12. Spontaneous Combustion=>The type of combustion in which a material suddenly bursts into flames,
without the applications of any apparent cause is called spontaneous
combustion.
13. Explosion=> A
large amount of gas formed in the reaction is liberated. Such a reaction is
called explosion.
14. Luminous=> Giving
off a very bright light or a person or trait considered glowing.
15. Calorific Value=> The amount of heat energy produced on complete combustion of 1kg of
a fuel is called calorific value.
16. Kilojoule per kg (kJ/kg) => The calorific value of a fuel is expressed in a unit called kilojoule
per kg (kJ/kg).
1 17. Incomplete Combustion => A reaction or process which entails only partial burning of a
fuel. This may be due to a lack of oxygen or low temperature, preventing the complete chemical reaction. Carbon monoxide is produced as a byproduct from incomplete combustion of
carbon.
18. Global Warming => Global warming is a rise in temperature of the atmosphere of the earth .This results, among other things, in the melting of polar glaciers,
which leads to a rise in the sea level, causing floods in coastal areas. Low lying coastal areas may even be
permanently submerged under water.
19. Acid Rain=> Oxides
of sulphur and nitrogen dissolves in rain water and form acids. Such acids are
called rain acid. It is very harmful for crops, buildings and soil.
20. Deforestation => Trees provide us with useful substances which are lost
when wood is used as fuel. Moreover cutting of trees leads to deforestation
.Which is quite harmful for our environment.
21. Ideal Fuel =>An
ideal fuel is cheap, readily available, readily combustible and easy to
transport. It has high calorific value. It doesn’t produce gases or residues that pollute the environment.
22. Fuel Efficiency => fuel efficiency is a measure of how far a vehicle can travel
per unit of fuel. In the United
States, this is expressed as “miles per gallon” (mpg). Fuel efficient vehicles
require less gas to go a given distance.
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