The sentences are invalid and unsound.
The fire is defined as the vigorous oxidation of a substance. Now oxidation can occur in presence of any oxidising agent. Like magnesium in presence of nitrogen in high temperature with a dazzling brownish flame to produce magnesium nitride. So fire can be produced in absence of oxygen.
Oxygen is present everywhere in world. So production of a whole room without oxygen is very tough to produce and costly process. So its very unsound.
