Some of the stars you see in the night sky are already gone. Why is it possible to still see their light?

they are light years away

Explanation:

when you look at the sky you are looking at about 6 million years in the past because time travels differently between space and our atmosphere. That's why astronauts can feel like they have been gone for 3 days but really for 3 months.

Key point:

Light travels differently between space and Earth

it is prolly d and c and f

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure