Which solution is a buffer? which solution is a buffer? a solution that is 0.200 m in h2so4 and 0.200 m in na2so4 a solution that is 0.200 m in h3po4 and 0.200 m in nah2po4 a solution that is 0.200 m in h3po4 and 0.200 m in nabr a solution that is 0.200 m in h3po4 and 0.200 m in hbr?