Calculate levels of lead in blood; density, concentrations, etc

44. The concentrations of lead in blood samples are often reported in units of micromoles of lead per liter of blood. Calculate the value of the concentration in these units of a blood sample containing 45 ppb lead, assuming that the density of blood is one gram per milliliter. Please only answer if you're 100% positive! My computer program is picky and likes to tell me the answers are wrong! Thanks :)

Calculate fraction of cyanide existing as the anion; pH, etc

100. For HCN in water, Ka = 2.0E-10. Calculate the fraction of cyanide that exists as the anion rather than in the molecular form at pH values of 4, 7, and 10 (provide answers in that order). Please only answer if you're 100% sure you're right. My computer program is very picky and likes to tell me the answers are wrong! Thanks :)

Calculating pE value; equilibruim; volume of O2; and pH

19. What is the pE value in a solution in equilibrium with air (18% O2 by volume) at pH 6.00? ******PLEASE do this only if you're 100% positive you're right. My computer (program) is very picky and likes to tell me the answers are wrong :( Thanks!

Calculating pE values

20. What is the pE value in an acid mine water sample having [Fe3+] = 6.79E-3 M and [Fe2+] = 4.14E-4 M? ******PLEASE do only if 100% positive you're right. My computer program is very picky and likes to tell me the answers are wrong :( Thanks!

pH, ionization, acid dissociation.

29. The pH of a sample of rain is found to be 3.3. Calculate the percentage of HSO4- that is ionized in this sample, given that the acid dissociation constant for the second stage of ionization of H2SO4 is 1.2E-2. PLease do this only if you are 100% positive you're right. My program is very picky and likes to tell me the answer's are wrong :( Thanks!