Answer:
Please note that the question is incorrectly formatted. It should read:
“How many moles of Na 2 CO 3 are in 10.0 mL of a 2.0 M solution?” (Note the subscripts. Without them, the question makes no sense.)
When a solution is called 2.0 M (molar), it has 2 moles of compound dissolved in 1 liter of water. So how many moles would there be in 10 ml?
(1L =) 1000 ml = 2 moles
10 ml = x moles.
Cross-multiply: x = 10*2/1000 = 0.02 moles.
(Or alternatively, 10 ml is 100 times less than 1 L so you also have 100 times less moles.)
