By your reasoning, that same room should have all the oxygen near the floor with the nitrogen hovering above. In spite of the difference in density between methane and air, they stay mixed even in a closed room because of convection currents. read more
The typical method of air separation to component gases is super-refrigeration. Bearing in mind that there is hardly any methane in air to begin with, it is easier to get it all than to extract the oxygen or nitrogen. In order of descending temperatures - methane condenses at 111.7 K; oxygen at 90.2 K; nitrogen at 77 K. read more
Yes. Methane (CH4) is the dominant gas in natural gas mixtures. Any carbon based fuel when combusted can create soot. With methane, the soot tends to be light and feathery unlike oil-based soot. But it is still soot, incompletely combusted carbon. When properly and completely burned, methane yields carbon dioxide and water vapor. read more