I have a problem with using word "gas". In my language we have two completely different words for gas that is put in car and gas that is used in stove when cooking something. Should I use phrase "natural gas" when talking about gas that is used for cooking (or when talking about car that uses LPG / CNG) and gas when talking about gasoline used in cars? I am referring to american english, since brits use word petrol which is easier to explain in this context, at least I think.
In American English the definition of the word "gas" is entirely dependent on the context. In American English, we have two separate words as well, gasoline for petrol as the brits would call it and gas for either the state of matter or for natural gas. However, people do not always use the language as intended and choose to abbreviate words. This may lead to a certain amount of ambiguity but that is why context is often necessary to figure out which definition to use. If someone says, "I walked through the kitchen, and as I passed by I smelled what I thought to be gas" then you can be almost certain that they are talking about the scented natural gas that is used in stoves and not gasoline. However, if they say, "I went to go fill up my car with gas" then you can be almost certain that they mean gasoline.
The reason I say "almost certain" and not just "certain" is that people may very well mean the other word/definition and it is still justified. You can make assumptions but they may not always be right. You don't have to use gas for the word gasoline, you can use natural gas instead of just gas. Just know that others might, and that context or further questioning might be necessary to understand the true meaning.