What is the molarity of a solution, made from 10 mL of a 1.00 M solution, and then diluted by adding 90 mL water?

0.10 M

Explanation:

use the dilution equation (Volume 1)(Molarity 1)=(Volume 2)(Molarity 2)

plugging in the numbers. (10 mL)(1.00 M)=(10 mL+90mL)(X M)

solving for X M=(10 mL x 1.00 M)/(100 mL)

gives you 0.10 M solution