Define combustible and non-combustible materials with examples.
Combustible substances : Those substances which undergo combustion or burn are called combustible substances.
For example: Paper, cloth, cooking gas (LPG), CNG, Kerosene oil, wood, charcoal, etc.
Non-Combustible substances : Those substances which do not undergo combustion are called combustible substances.
For example: Stone, cement, bricks, soil, sand, water, iron nails, etc.