You have a freshly prepared .01 M ascorbic acid (vitamin C) solution. Each liter of this solution contains how many ascorbic acid molecules?
In order to be able to find the number of molecules of ascorbic acid you get per liter of that solution, you need to know how many moles of ascorbic acid you have per liter of solution.
#color(blue)("molarity" = "moles of solute"/"liters of solution")#
Since your solution has a molarity of
Now, you know that one mole of any substance contains exactly
In your case,
#0.01color(red)(cancel(color(black)("moles"))) * (6.022 * 10^(23)"molecules")/(1color(red)(cancel(color(black)("mole")))) = 6.022 * 10^(21)"molecules"#
Rounded to one sig fig, the answer will be
#"no. of molecules" = color(green)(6 * 10^(21)"molecules")#