Conversation so far:
is crude petroleum a solution or mechanical mixture
Petroleum is a mixture of a very large number of different hydrocarbons.
what is petroleum made of
The most commonly found molecules in petroleum are alkanes (paraffins), cycloalkanes (naphthenes), aromatic hydrocarbons, or more complicated chemicals like asphaltenes.
is petroleum natural
Petroleum (pronounced /pəˈtroʊliəm/) is a naturally occurring, yellowish-black liquid.
where is petroleum found
Petroleum is found in geological formations beneath the Earth's surface.

Question: why do humans need the liquid
Self-contained rewrite: why do humans need petroleum