An ocean food chain is shown.

Which organism is a tertiary consumer?

clownfish
brittle star
killer whale
octopus

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

it means there are 3 atoms of oxygen