Answer : The concentration of the NaOH is, 0.234 M
Explanation :
Using neutralization law,

where,
= basicity of an acid = 1
= acidity of a base = 1
= concentration of KHP = 0.500 M
= concentration of NaOH = ?
= volume of KHP = 25 ml
= volume of NaOH = 53.5 ml
Now put all the given values in the above law, we get the concentration of the NaOH.


Therefore, the concentration of the NaOH is, 0.234 M