Question

Which of the following is not a combustible substance?
A. Camphor
B. Glass
C. Straw
D. Alcohol

Answer 1

Hint: Combustible materials are those which can be easily ignited and burned. The combustible substances can be burned in the presence of air giving out heat and light.

Complete Solution :
There are many substances which can be burned in the presence of air as it has presence of oxygen in it, which acts as a catalyst for the combustion. There are two types of combustion which takes place in nature, complete combustion and incomplete combustion. In the complete combustion, the material is burned completely leaving no residue or carbon and incomplete combustion is the one where the substance leaves a residue after getting burnt.

- Now, if we look at the substances mentioned above, we would notice that the first one is the camphor which is combustible because you might have seen it getting used during worshipping or it is burnt to purify the air too, hence it is combustible.
- Glass can be liquified under high pressure and temperature but it is not combustible as it cannot be burned in the presence of air, hence, it is not combustible.
- Straw is basically the fodder for domestic animals and organic substances which can be easily burned in the presence of air. Hence, it is combustible.
- Alcohol is made of carbon and hydrogen bonds between it and it is highly combustible in presence of air. When it reacts with air, it forms carbon dioxide and water.
So, the correct answer is “Option B”.

Note: Most of the students remain confused between combustibility and flammability. Flammability is a degree applied to combustible substances to know how fast they can be burned. When it is written that a substance is highly flammable, it means that substance can easily catch fire at room temperature itself.