The balanced chemical equation for the neutralization reaction between NaOH and HCl is:

NaOH + HCl → NaCl + H2O

To determine the molarity of the HCl solution, we can use the formula:

Moles of HCl = Molarity of NaOH × Volume of NaOH (in liters)

First, we need to convert the volume of NaOH from milliliters (mL) to liters (L):

Volume of NaOH = 27.0 mL = 0.027 L

Now, we can calculate the moles of HCl:

Moles of HCl = 0.45 M × 0.027 L = 0.01215 moles

Next, we need to find the volume of HCl solution that reacted with the 0.01215 moles of HCl. Let's assume the volume of HCl solution is V liters.

Molarity of HCl = Moles of HCl / Volume of HCl (in liters)

0.20 M = 0.01215 moles / V

Solving for V, we get:

V = 0.01215 moles / 0.20 M = 0.06075 L

Therefore, the molarity of the HCl solution is 0.20 M, and the volume of HCl solution required for neutralization is 0.06075 L or 60.75 mL.