Phylogenetic tree, explain how you know if two organisms are closely related

Explanation:

In a phylogenetic tree, the relatedness of two species has a very specific meaning. Two species are more related if they have a more recent common ancestor, and less related if they have a less recent common ancestor. ... That's because, by default, the horizontal axis of the tree doesn't represent time in a direct way.

heat a spark and oxygen

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds