Methyl orange gives $.......$ color in an acidic medium.

The suitable indicator for the titration of a strong acid and a weak base is:

Which indicator is most suitable for the titration of $0.1 \, N \, Na_2CO_3$ solution with $0.1 \, N \, HCl$?

The different colours of litmus in acidic, neutral and basic solutions are, respectively.

The rapid change of $pH$ near the stoichiometric point of an acid-base titration is the basis of indicator detection. 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 the expression:

$50 \ mL$ of $0.1 \ M$ of a weak acid $HA$ is titrated with $0.1 \ M$ of $NaOH$. The ionization constant of $HA$ $(K_a)$ is $1.8 \times 10^{-5}$. Using the given information and from the options shown below,the best indicator for the titration of $HA$ with $NaOH$ is $....$