Name the acid-base indicator extracted from lichen.

(a) Acid have a --------tasks and they turn -------litmus to --------

(b) Substance do not show their acidic properties without ----------

(c) Acids produce ------- ions on dissolving in water.

(d) Those substance whose smell (or odour) changes in acidic or basic solutions are called ------indicators.

(e) Onion and vanilla extract are ------ indicators.