What is the concentration of the NaOH solution, if in a titration, 20 mL of NaOH reacts with 19.82 mL of 0.1018M HCl ?

This is an acid base
reaction:

HCl + NaOH -> H2O +
NaCl

The mole ratio is 1:1 (1 mole of HCl to 1 mol of
NaOH)

Now, we'll have to find the number of moles of
reactant HCl:

n =
0.1018*0.01982

n = 0.002 mol of
HCl

Now, we'll determine the concentration of NaOH, using
the equality:

M(HCl)*V(HCl) =
M(NaOH)*V(NaOH)

M represents the molarity of acid or
base

V represents the volume of acid or
base

0.002 =
0.02*M(NaOH)

M(NaOH) =
0.002/0.02

M(NaOH) = 0.1
[mol/L]