At pH 6.0 the N-terminus of His-His-His-His would have a (positive/ negative) charge. The C-terminus would have a (positive/ negative) charge. Since the pKa for His is 6.0, essentially half of the residues would carry a (negative/ positive) charge on their side chains, so that the charge per residue could be considered to be (+2.0/ +0.5 / +1.0/ +1.5). The result would be a net charge on the tetrapeptide of (+2.0/ -1.0/ +1.0/ -2.0). The tetrapeptide would be (more/ less) soluble in water than Histidine itself. When the bonds are formed between the carboxylate and amino groups to form the tetrapeptide, the groups that would interact with water are lost.

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.