please tell me Why

The critical angle is the angle of refraction in a medium when the angle of the incident radiation is 90 Select one: TRUE FALSE During the experiment of potentiometric titration of 20 mL of 0.3M of a weak acid with 0.3 M NaOH. How much of NaOH should be added to 20 mLof the weak acid to make the pH = 7 A. Less than 20 ml B. More than 20 ml C. Equal to 20 ml What is the factor that does not affect refractive index? A. Temperature B. Optical density C. Wavelength of the light D. Angle of incidence E. All of them affect refractive index