Two substances excreted by the kidneys are and

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides

b. lithosphere, asthenosphere, mesosphere   is the answer most likely

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.