Step-by-step explanation:
The given data is as follows.
= ?,
= 0.85 M
= 185 mL,
= 35.7 mL
where,
is concentration of acid
is the volume of acid
is the concentration of base
is the volume of base
According to the neutralization formula.
=

Now, substituting the given values into the above formula as follows.
=

=

= 0.164 M
Thus, we can conclude that concentration of acid is 0.164 M.