Petroleum is a fossil fuel that was formed from the remains of ancient marine organisms. Millions of years ago, algae and plants lived in shallow seas. After dying and sinking to the seafloor, the organic material mixed with other sediments and was buried. Over millions of years under high pressure and high temperature, the remains of these organisms transformed into what we know today as fossil fuels. Coal, natural gas, and petroleum are all fossil fuels that formed under similar conditions. Today, petroleum is found in vast underground reservoirs where ancient seas were located.
Assertion : Litter burning is not suggested by ecologists.
Reason : Burning litter enhances 'CO$ _2$'content of the air.
Litter burning is a common method of waste handling but it is not the best method of waste handling, because the nutrients in litter get converted into oxides and are lost from the ecosystem of the place. Over a period of time when wastes are burnt instead of recycling the nutrient status declines and consequently productivity will be less.