1. Which is an observation? a) Atoms consist of protons, neutrons, and electrons.
b) All matter is composed of atoms.
c) Water is colorless.
d) Atoms can form chemical bonds by sharing electrons.

the answer is 1. photosynthesis. glad to

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

c. heat from the poles back down towards the equator.