The following list contains some common polyatomic ions. Using the charge on these ions and the idea of valence, predict the formulas for the compound formed from the following:

nitrate NO3-1 phosphate PO4-3
sulfate SO4-2 acetate C2H3O2-1
ammonium NH4+1 chromate CrO4-2
carbonate CO3-2 dichromate Cr2O7-2
permanganate MnO4-1 sulfite SO3-2
ammonium and sulfite

A. (NH 4) 2SO 3
B. NH 4SO 4
C. (NH 4) 2SO 4
D. NH 4SO 3

Nanotechnology, the field of trying to build ultrasmall structures one atom at a time, has progressed in recent years. one potential application of nanotechnology is the construction of artificial cells. the simplest cells would probably mimic red blood cells, the body's oxygen transporters. for example, nanocontainers, perhaps constructed of carbon, could be pumped full of oxygen and injected into a person's bloodstream. if the person needed additional oxygen-due to a heart attack perhaps, or for the purpose of space travel-these containers could slowly release oxygen into the blood, allowing tissues that would otherwise die to remain alive. suppose that the nanocontainers were cubic and had an edge length of 24 nanometers. part a part complete what is the volume of one nanocontainer? (ignore the thickness of the nanocontainer's wall.) express your answer using two significant figures. v v = 1.4ă—10â’20 l previous answers correct significant figures feedback: your answer 1.3824â‹…10â’20 = 1.382ă—10â’20 l was either rounded differently or used a different number of significant figures than required for this part. if you need this result for any later calculation in this item, keep all the digits and round as the final step before submitting your answer. part b suppose that each nanocontainer could contain pure oxygen pressurized to a density of 81 g/l . how many grams of oxygen could be contained by each nanocontainer?