The pink colour of phenolphthalein in an alkaline medium is due to -

Phenolphthalein is a.......

Which indicator is used for the titration of a weak acid (oxalic acid) and a strong base (caustic soda)?

If a very small amount of $HPh$ (phenolphthalein) is added to a $0.1 \ M$ aqueous solution of $CH_3COONa$,the fraction of the indicator that exists in the colourless form is:
$[K_b(CH_3COO^{-}) = 10^{-9}, pK_a(HPh) = 9.6, \log 2 = 0.3]$

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

Which indicator is used for the titration of $CH_3COOH$ and $NaOH$?