Frank Cce Everyday Science Solutions for Class 8 Science Chapter 6 Combustion, Flame And Fuels are provided here with simple step-by-step explanations. These solutions for Combustion, Flame And Fuels are extremely popular among Class 8 students for Science Combustion, Flame And Fuels Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Frank Cce Everyday Science Book of Class 8 Science Chapter 6 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Frank Cce Everyday Science Solutions. All Frank Cce Everyday Science Solutions for class Class 8 Science are prepared by experts and are 100% accurate.

Page No 93:

Answer:

Page No 93:

Answer:

(b) iron

Iron is a non-combustible substance because it has a high ignition temperature.

Page No 93:

Answer:

(a) non-luminous zone

The non-luminous zone is hotter than the luminous zone and is the hottest zone.

Page No 93:

Answer:

(a) and (d)

Water is not used to put out an electrical fire as it conducts electricity and may result in the electrocution of the person trying to fight the fire.
Water is not used to put out an oil fire because, being heavier than oil, it sinks, and the oil continues to burn.

Page No 93:

Answer:

(b) dark zone

The dark zone is the zone where no combustion takes place.

Page No 93:

Answer:

(c) oxygen

Oxygen is not used as a fire extinguisher because it helps materials to burn.

Page No 93:

Answer:

(a) inflammable

Substances with very low ignition temperatures are inflammable.

Page No 93:

Answer:

(a) unburnt carbon

Unburnt carbon is an example of suspended particulate matter.

Page No 93:

Answer:

(a) low ignition and high calorific value

A good fuel has a low ignition temperature and high calorific value.

Page No 93:

Answer:

(b) gaseous fuel

Liquefied petroleum gas (LPG) is an example of a gaseous fuel.

Page No 93:

Answer:

(a) non-luminous

The non-luminous zone is the hottest zone of a flame.



Page No 94:

Answer:

Ice absorbs heat energy to melt and become water. As sawdust is an insulator of heat, ice take more time to absorb heat energy. Hence, it does not melt quickly when packed in sawdust.

Page No 94:

Answer:

On a rainy day, because of the higher humidity and lower temperature of the atmosphere, the rate of evaporation slows down. Hence, wet clothes dry slowly on a rainy day.

Page No 94:

Answer:

It is not advisable to sleep in a closed room with a smouldering fire because a smouldering fire produces carbon dioxide and many other gases that are not suitable for breathing. Hence, sleeping in a closed room with a smouldering fire may cause suffocation and death.

Page No 94:

Answer:

Matchsticks do not catch fire on their own because, to catch fire, any substance needs some temperature or energy called ignition temperature. Matchsticks get this energy when they are rubbed or struck against the striking pad on the matchbox.

Page No 94:

Answer:

Water is heavier than petrol, because of which it sinks and petrol comes up. Because of this, water is not an effective extinguisher of fires caused by the burning of petrol. Hence, water is not used in such cases because petrol keeps burning even in presence of water.

Page No 94:

Answer:

1. Water and glass are non-combustible substances.
2. Substances that burn easily are called combustible substances.
3. A candle flame consists of four important zone.
4. Combustion is of two types.
5. A liquid fuel used in homes is kerosene.

Page No 94:

Answer:

Column A Column B
1. Combustible (d) Petrol
2. Non-combustible (f) Sand
3. Ignition temperature (a) Kindling temperature
4. Flame (b) Zone of combustion
5. Water (c) Fire extinguisher

Page No 94:

Answer:

1. True

2. False
The burning of liquefied petroleum gas (LPG) is rapid combustion.

3. True

4. False
The dark zone, or the zone of no combustion, is the coolest zone.

5. False
SO2 in air causes acid rain.



Page No 95:

Answer:

Substances that burn easily are called combustible substances.

Page No 95:

Answer:

Substances that catch fire easily and have very low ignition temperatures are called inflammable substances.

Page No 95:

Answer:

The burning substance will stop burning if we cut the air supply to it.

Page No 95:

Answer:

A fire extinguisher is a device used to extinguish or stop a fire.

Page No 95:

Answer:

The fuels that directly produce heat on ignition are called primary (natural) fuels. They are used in their natural forms.

Page No 95:

Answer:

Carbon dioxide gas is formed as a result of complete combustion. Carbon monoxide, which is a poisonous gas, is formed as a result of incomplete combustion.

Page No 95:

Answer:

SPM stands for suspended particulate matter.

Page No 95:

Answer:

Carbon dioxide is responsible for global warming.

Page No 95:

Answer:

Water, glass and cement are non-combustible substances.

Page No 95:

Answer:

Dry paper starts burning when a burning matchstick is brought near it. Rapid combustion occurs in this case.

Page No 95:

Answer:

The amount of heat produced on the complete combustion of one kilogram of a fuel is known as its calorific value. It is usually expressed in kilojoule per kg (kJ/kg).

Page No 95:

Answer:

Luminous flame Non-luminous flame
It is yellow in colour. It is blue in colour.
It produces heat and a good amount of light. It produces a very little amount of light.
It is produced by incomplete combustion. It is produced by complete combustion.

Page No 95:

Answer:

The lowest temperature at which a substance starts burning after catching fire is known as its ignition (kindling) temperature.

Page No 95:

Answer:

Combustible Non-combustible
A substance that burns easily A substance that does not burn in air or oxygen
Examples: Paper and kerosene Examples: Water and glass

Page No 95:

Answer:

Dry grass at some places attains its ignition temperature and catches fire during the extreme heat of summer. It is a type of extreme combustion in which fire spreads from grass to a forest and becomes difficult to control. This type of fire results in a loss of life and property.

Page No 95:

Answer:

Carbon monoxide is a harmful gas because it reduces the oxygen-carrying capacity of blood. During respiration, oxygen molecules enter the lungs and are then carried by red blood cells, where they bind with haemoglobin, forming a complex known as oxyhaemoglobin. If carbon monoxide enters the lungs, then it reacts with haemoglobin to form a very stable complex, carboxyhaemoglobin (which is 300 times more stable than oxyhaemoglobin). It prevents haemoglobin from carrying blood, which results in suffocation, leading to death.

Page No 95:

Answer:

Complete combustion Incomplete combustion
This process takes place in the presence of an adequate amount of air or oxygen. This process takes place when oxygen supply is insufficient.
Carbon dioxide, water , heat and light are the products of complete combustion. Carbon monoxide, soot, water, heat and light are the products of incomplete combustion.

Page No 95:

Answer:

Fuels are classified into the following types depending upon how they exist in nature.

(i) Solid fuels: Examples - Coal and wood.
(ii) Liquid fuels: Examples - Petrol and diesel.
(iii) Gaseous fuels: Examples - LPG and biogas.

Page No 95:

Answer:

Acid rain is caused by the production of oxides of sulphur and oxides of nitrogen as a result of the burning of coal, diesel and petrol. These oxides dissolve in rainwater, forming acids, and cause acid rain.

Page No 95:

Answer:

A fire extinguisher is a device that is used to stop or extinguish fires. Fire extinguishers, usually red cylinders, are commonly found in cinema halls, banks and other public buildings.

Page No 95:

Answer:

The following are the conditions necessary for combustion.

(i) Presence of a combustible substance: For combustion to take place, substances that are combustible should exist.

(ii) Presence of a supporter of combustion: Generally, combustion occurs in the presence of air or oxygen. A supporter of combustion is a substance that helps in combustion.

(iii) Attainment of ignition or kindling temperature: Ignition or kindling temperature is the temperature at which a substance catches fire and starts burning. Every substance has a particular ignition temperature. Example: The ignition temperature of white phosphorous is 35⁰C.

Page No 95:

Answer:

The following are the five characteristics of an ideal fuel.

1. It should have a high calorific value.

2. The products of burning should not be hazardous to health.

3. It should not cause environmental hazards.

4. It should be easily available and cheap.

5. The ignition temperature should be above the room temperature.

Page No 95:

Answer:

When water is poured on a burning substance, it cools the substance below its ignition temperature, and the fire is extinguished. Moreover, water vapour surrounds the burning substance and the air supply to it stops. In this way, water helps in extinguishing a fire.

Page No 95:

Answer:

Domestic LPG (liquefied petroleum gas) is better than wood for the following reasons.

(i) LPG is a pollutant-free, clean fuel, whereas wood produces many pollutants on burning

(ii) LPG has a higher calorific value of 55000 than wood.

(iii) It does not have any hazardous effect on health, whereas smog or gases that are produced by the burning of wood from incomplete combustion have harmful effects on the environment and health.

(iv) It is easy to handle, transport and store.

(v) Its use helps reduce deforestation.

Page No 95:

Answer:

The characteristics of an ideal fuel that we must keep in mind while purchasing it are as follows.

1. It should have a high calorific value.

2. It should not produce any hazardous products on burning.

3. It should not cause much air pollution.

4. It should be readily available and cheap.

5. It should be easy to handle, transport and store.

6. Its ignition temperature should be above the room temperature.

Page No 95:

Answer:

Page No 95:

Answer:

The following are the principles used in putting out a fire.

1. Bring the temperature below the ignition temperature.

2. Stop the supply of air.

Page No 95:

Answer:

When we boil water in a paper cup using a candle flame, the heat supplied by the flame quickly transfers to the water from the paper cup and it starts boiling. During this process, the heat is transferred from the paper cup to the water, and the cup does not reach its ignition temperature. So, the water boils without the paper cup burning.

Page No 95:

Answer:

A flame is defined as a glow that is produced when a substance undergoes combustion. A flame is produced only by those substances that vaporise during burning.

A flame has four zones:
i) The non-luminous zone or the zone of complete combustion:
It is the blue, outermost zone of a flame where complete combustion takes place. It is faintly visible and is the hottest zone of a flame.

ii) The luminous zone or the zone of incomplete combustion:
It is the pale yellow zone of a flame where incomplete combustion takes place because of insufficient supply of air.

iii) The dark zone or the zone of no combustion:
It is a black-coloured zone that is located around the wick. In the dark zone, no oxygen is available for burning; hence, no combustion occurs.

iv) The blue zone:
It is the zone that is the least hot and is present near the bottom. The blue colour is due to the burning of carbon monoxide, which is produced because of incomplete combustion of carbon particles.

Page No 95:

Answer:

Fuels are classified into the following types on the basis of their sources.
(i) Natural source (or primary) fuels: These fuels occur in nature and are used in their natural form.
Examples: Wood, coal, natural gas, animal-dung cake and crop residue.

(ii) Processed (or secondary) fuels: The fuels that are prepared from primary fuels are called secondary or processed fuels.
Examples: Coke, diesel, petrol, charcoal and kerosene.



View NCERT Solutions for all chapters of Class 8