Solutions ph volume

can anyone explain this please
which one of the following solutions reacts with an equal volume of 0,05M Ba(OH)2 giving a pH=7 solutions?
a)0,1 M HClO4
b)0,1M KCl
c)0,1M NH3
d)0,1M CH3OH
e)0,1M NaOH
the answer is a
thanks

ba(oh)2 is a base
you want a solution with ph 7 which means you want a salt
a reaction between acid and base gives you salt so you need to find in the options below which is acid,which is option a
kcl is salt
nh3 base,ch3oh and naoh are bases
so correct option is a

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