A 25.0 mL solution of a monoprotic weak acid is titrated with 0.10 M NaOH. The equivalence point is reached after 38.52 mL of NaOH has been added. What was the initial concentration of the weak acid

0.154 M

Explanation:

In case of titration , the following formula can be used -

M₁V₁ = M₂V₂

where ,

M₁ = concentration of acid ,

V₁ = volume of acid ,

M₂ = concentration of base,

V₂ = volume of base .

from , the question ,

M₁ = ? M

V₁ = 25.0mL

M₂ = 0.10 M

V₂ = 38.52 mL

Using the above formula , the molarity of acid , can be calculated as ,

M₁V₁ = M₂V₂  

Putting the respective values ,

M₁ * 25.0mL =  0.10 M * 38.52 mL

M₁ = 0.154 M

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first one is the correct answer