I need help with questions 7-9.

7. Try these below: Stock Conc Desired Conc. in Working Solution 0.1 M 1M n-fold Dilution Final Volume of Vols. of Stock (Stock/DesiredWorking. and Water to Solution Pipet 10 100 mL 10 mL (+90 ml water) 5.5 50 mL 9.1 mL (+ 40.9 mL water) 150 mL 2.2 M 0.4M 0.5 M 5 mM 4M 0.5 M 200 mL 0.2 M 2 mM 200 mL 0.2 M 20 mM 400 ml 8. Q: What if you had a stock solution = 0.5 M and you need a working solution of 1.0 M ? Note that often times, stock solutions are supplied as 10 X or 100 X concentrates, meaning the n-fold dilution will be 10 or 100, respectively, for a working solution at 1X final concentration (typical). [The number in front of the X is the n-fold dilution to prepare a 1X working solution] 9. You have a 20 X Stock solution, how would you prepare 1 L of Working Solution at 1 X final Your answer here: concn