Medium
The example of self-combustion (spontaneous) is -
Explanation
Explanation
White phosphorus is so reactive that it can catch fire on its own when exposed to air at room temperature, without needing an external flame — this is called spontaneous or self-combustion. Carbon, petrol, and diesel all need an external source of ignition (like a spark or flame) to burn. So the correct answer is Phosphorus, option (2).
PRO TIP
Re-check your working by substituting the answer back into the original question.