As we look around space we find that most of it is composed of (4). hydrogen combines with carbon which is the basis for all living things. Combining different (6). A group of two or more atoms that are bonded together is called a (7). are combined in a specific way, or ratio, the substance is called a (8). of hydrogen. When the forms a (5)_ 7. together form different substances. 8. _. And when the elements (e.g. water).
