Question

a person sleeping in a closed room with burning coal feels suffocated after some time? why?

Answer 1

There are two reasons for suffocation. Firstly the burning of coal takes the oxygen in the room for combustion. Ad the next reason is the extreme amount of smoke emitted by the coal on burning which fills the atmosphere with harmful gases. Is also the reason for suffocation.

Answer 2

this is because the burning coal uses all oxygen present in that room and emits harmful gases and the person doesn't get  enough oxygen for breathing.so he/she feels suffocated.