when preparing diluted solutions, the following formula is used,
c1v1 = c2v2
where c1 is concentration and v1 is volume of concentrated solution
and c2 is concentration and v2 is volume of the diluted solution to be prepared
substituting the values in the equation
1.00 M x 5.000 x 10⁻¹ L = C x 2.50 L
C = 0.200 M
the concentration of the diluted solution is 0.200 M