100 ml is drawn from 0.1 m solution of kcl and added to 900 ml of water. what is the
new concentration?

The new concentration will be 0.01 M.

Explanation:

To determine the new concentration we use the following formula.

concentration (1) × volume (1) = concentration (2) × volume (2)

concentration (1) = 0.1 M

volume (1) = 100 mL

concentration (2) = unknown

volume (2) = 100 mL + 900 mL = 1000 mL

concentration (2) = [concentration (1) × volume (1)] / volume (2)

concentration (2) = (0.1 × 100) / 1000 = 0.01 M