The flask shown here contains 10.0 ml of hcl and a few drops of phenolphthalein indicator. the buret contains 0.270 m naoh. what volume of naoh is needed to reach the end point of the

The concentration of HCl was probably provided in the figure that is missing.
The equation for this neutralization is:
NaOH + HCl → NaCl + H₂O
Its is visible from the equation that the moles of NaOH required will be equal to the moles of HCl present.
moles = concentration (mol/L) x volume (L)
moles HCl = moles NaOH
[HCl] x 0.01 = 0.270 x V
V = (0.01[HCl])/0.270 L

Outermost (valence) electrons