Quick questions on Acid-base titrations and curves: TCE Chemistry (Tasmania)

The indicator must change colour within the steep vertical part of the curve, so that one drop of titrant carries the pH through the colour change. Match the indicator's $pK_a$ (its working range, roughly $pK_a \pm 1$) to the equivalence pH.

A titration curve carries more information than just the equivalence point. The initial pH reflects the strength and concentration of the analyte: a strong acid starts very low, a weak acid starts noticeably higher for the same concentration. The half-equivalence point lies at half the equivalence volume and, for a weak acid, gives $\text{pH} = pK_a$ directly. The equivalence volume itself lets you calculate the unknown concentration through the mole ratio, exactly as in volumetric analysis.