For which of the following titrations is phenolphthalein the most suitable indicator?

For an acid-base indicator,the dissociation constant $K_a = 1.0 \times 10^{-5}$. The indicator is red in acidic form and blue in basic form. What is the $pH$ range required for the color change from $80\%$ red to $80\%$ blue?

In an acid-base titration,the rapid change in $pH$ near the equivalence point depends on the indicator used. The $pH$ of the solution is related to the ratio of the concentrations of the conjugate acid $(HIn)$ and base $(In^-)$ forms of the indicator by which equation?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Phenolphthalein is a $pH$ dependent indicator,remains colourless in acidic solution and gives pink colour in basic medium.
Reason $R$: Phenolphthalein is a weak acid. It doesn't dissociate in basic medium.
In the light of the above statements,choose the most appropriate answer from the options given below.

The $pH$ range of methyl orange as an indicator is in between:

Which indicator works in the $pH$ range of $8 - 9.8$?