Question

solve the riddle!coffee is brown and bitter in taste.is it acid or base?don't give answer without any test you are in dark with it's taste.

Answer 1

its an acid as it tastes sour little bit

Answer 2

It is mostly a base because:
1.It tastes bitter
2.The brown compounds are $PbO_{2}$ and $Fe(OH)_{3}$, both of which are basic.
But it shows slight characteristics of acids like:
1.It does not corrode (as viscously as bases do)