Question

why we are not advised to sleep in a room having closed doors and windows with a coal burning by inside ????

Answer 1

because the burning coal emits the gas which combines with the oxygen in our room and forms carbonmonoxide and cabondioxide gas which are harmful if we breathe

Answer 2

Because when coal burns in a closed room it is unable to burn completely as a result it burns partially and produces Carbon monoxide which is a poisonous gas and even causes depletion of oxygen in the room

and may cause fatal results such a death of the sleeping person

hope it helps