A small generic section of the primary structure of an a helix is given below. ?amino acid1 ?amino acid2 ?amino acid3 ?amino acid4 ?amino acid5 ?amino acid6 ?amino acid7? (a) Which amino acid residue?s backbone forms a hydrogen bond with the backbone of the sixth (6th) residue? Choose the correct residue from the drop-down menu. amino acid Select answer (b) Which of the following peptide segments is most likely to be part of a stable a helix at physiological pH? (c) How many hydrogen bonds can be formed within the backbone of 7 residues? Do not count the hydrogen bonds between this section and outside the section

Determine the  wavelength of light emitted when an electron  in an li2+ ion  makes a transition from an orbital with n  =  6 to an orbital with n  = 5.

Answerthis solution will not form a precipitateexplanationsolubility equilbrium:         pbf₂(s)  ⇄ pb²⁺(aq) + 2 f⁻(aq)the solubility product expression is    (we exclude solids from the equilibrium expression).now suppose we have the trial ion product q, which we can define as    then, we can interpret  q as the product of the concentration of the ions that we have and ksp as the product of the ion concentrations that are needed to form a saturated solution.if q > ksp, then that implies that there will be a surplus of ions that exceed the amount that is required to form a saturated solution. a precipitate will then form (the precipitate continually  forms until the surplus ions are removed and q is decreased to ksp's value).if q = ksp, the saturated solution that forms is barely saturated and the precipitate will be minimal.if q < ksp, then the ion concentration will not be enough to form a saturated solution (so no precipitate).using our information, we calculate the trial ion product:     since q = 2.7  × 10⁻⁸ < ksp =  4  ×  10⁻⁸, a precipitate will not form.