The question is incomplete. Complete question is
What volume of naoh is required to flip the indicator from colorless to pink at the endpoint?a) 1 drop
(b) 0.1 mL
(c) 0.5 mL
(d) 1 mL
(e) the volume will vary
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Answer: Correct answer is option e. the volume will vary
Reason:
The colour of indicator, depends upon the pH of solution. For instance, in an acid-base indication, as in case of NaOH Vs HCl, phenolphthalein is used as in indicator. In acidic medium, phenolphthalein is colourless while in basic medium phenolphthalein. So, if the concentration of acid is more, more amount of NaOH will be required to flip the colour of indicator. Similarly, less amount of NaOH will be required in case of dilute acid solution. Thus, volume of NaOH is required to flip the indicator from colorless to pink at the endpoint will vary and it will depend on conc. of acid.