It is incorrect to say that a compost pit helps in burning away plastic wastes because plastics are non-biodegradable and cannot be composted:
Explanation
Plastics are made of non-biodegradable polymers, such as polyethylene. Microorganisms in soil take hundreds of years to decompose plastics.
Composting
Composting is a safe way to manage organic waste, but it is not suitable for plastics. Composting is a process that breaks down biodegradable organic wastes into manure. Some examples of biodegradable organic wastes that can be added to a compost pit include vegetable peels and paper.
Burning plastic
Burning plastic waste, such as bottles, bags, and wrappers, produces highly toxic carbon monoxide (CO) gas.