Question

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?

Answer 1

Buffer is formed from weak acid and its salt with strong base (its conjugate base)
So the only one correct answer is :
0.2 M H₃PO₄ and 0.2 M NaH₂PO₄ 
While all other choices are incorrect