Q. Which of the following are correctly matched?

1. Rapid combustion- produces heat and light
2. Spontaneous combustion- phosphorus
3. Explosion- coal dust

Select the correct answer from the codes given below:
Answer: Only 2 and 3
Notes: The gas burns rapidly and produces heat and light. Such combustion is known as rapid combustion. There are substances like phosphorus which burn in air at room temperature. The type of combustion in which a material suddenly bursts into flames, without the application of any apparent cause is called spontaneous combustion. Spontaneous combustion of coal dust has resulted in many disastrous fires in coal mines. When a cracker is ignited, a sudden reaction takes place with the evolution of heat, light and sound. A large amount of gas formed in the reaction is liberated. Such a reaction is called explosion. Explosion can also take place if pressure is applied on a cracker.