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Which of the following is a clear example of SPONTANEOUS combustion?
ABurning of LPG when the kitchen stove is turned on
BA coal-mine fire that starts on its own due to slow heating of coal dust
CBursting of a cracker on Diwali
DA matchstick lit by rubbing on the matchbox
Answer & Solution
Correct answer: B. A coal-mine fire that starts on its own due to slow heating of coal dust
Spontaneous combustion is combustion that begins without any external ignition, usually because the substance heats up to its ignition temperature by itself (e.g. slow oxidation in heaped coal dust, or piles of oily rags). The other options need an external trigger (rubbing, switch, ignition) — so they are not spontaneous.
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