The OH- concentration in a 2.5 x 10-3 M Ba(OH)2 solution is A) 1.2 x 10^-2 M.
B) 2.5 x 10^-3 M.
C) 5.0 x 10^-3 M.
D) 4.0 x 10^-12 M.

Answer : C) 5.0 x 10^-3 M
if the concentration of Ba(OH)2 is 2.5 x 10^-3 M

then the OH- concentration is twice this so your answer is C.

1.from liquid state to gaseous state is evaporation 3.solid to liquid is melting 5. solid to gaseous state is sublimation 6. gas to solid state is decomposition 7. a change of state is known as the states of matters