Give scientific reasons for the burning of cooking gas is a fast change.
Give scientific reasons for the burning of paper is an irreversible change.
Give scientific reasons for the burning of fuels may be an undesirable change.
Burning of liquified petroleum gas (LPG) for cooking food is a desirable change.
Classify the following changes into fast and slow changes:
Explosion of a cracker, tooth decay, growth of a plant, fading of flowers, burning of cooking gas, taking x-ray photograph of a body part