Answer:
5.1 x 10^-3 M
Step-by-step explanation:
Find number of moles of KOH used
.050 M /L * .017 L = .00085 moles of KOH
from the reaction equation, this will react with 1/2 as many moles of Ca 2+
or .000425 moles of Ca <===== in .084 Liter of water
.000425 moles / .084 liter = .00505 M =~ 5.1 x 10^-3 M