Large areas around the globe with similar climates and similar communities of organisms form a
a population.
b
a biome.
c
an ecosystem.
d
a species.

a biome

Explanation:

a species is a type of animal kind, a population is the number of a certain species, an ecosystem is basically a big web of nature that is connected. so we can rule those 3 out. a biome is a part of land with similar climates and organism population

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