What type of anthropologist studies people from a perspective that considers how humans have adapted to their environments over time?

Biological Anthropologist

Explanation:

Biological Anthropologist studies human evolution,  variation and adaptation in relation to changes in the environment

i think its the first one

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