Question

The substance expected to have the highest ignition temperature
out of the following is
(a) kerosene (c) coal
(b) petrol (d) alcohol


NCERT Class VIII
Science - Exemplar Problems

Chapter 6. Combustion and Flame

Answer 1

Coal has an ignition temperature of 600 Celsius making it the highest among the given options.

Coal is a very important agent that finds its use in almost every sector.

It is one of the biggest natural resources that are being used. It is mainly a mixture of different carbonized matters.

Answer 2

The substance expected to have the highest ignition temperature out of the following is (c) coal.

Ignition temperature:

• The ignition temperature is the lowest temperature at which a material catches fire and undergoes combustion, releasing heat and light.
• In other words, it is the lowest temperature at which a flammable material, such as air or gas, must be heated before burning in the absence of a heat source.
• The ignition temperature of a material is the lowest temperature at which it begins to burn.
• The ignition temperature of a material is the lowest temperature at which the substance will spontaneously burn.

Ignition temperature of kerosene:

• The autoignition temperature of bulk kerosene fuel is roughly 295°C.

Ignition temperature of petrol:

• The auto-ignition temperature of gasoline (Petrol) is 400°C.
• Petrol catches fire at extremely low temperatures, resulting in a low ignition temperature.

Ignition temperature of Coal:

• Coal has an igniting temperature of roughly 580°C.

Ignition temperature of alcohol:

• Denatured alcohol has a flash point of 55°F (13°C).
• This means that, in the presence of an ignition source and oxygen, ethyl alcohol not meant for drinking can have its vapor generate a visible flame at a far lower temperature than ethyl alcohol intended for drinking.

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