Final answer:
None of the substances listed (milk, pure water, coffee, vinegar) are mildly basic. Milk is slightly acidic to neutral, pure water is neutral, coffee is acidic, and vinegar is acidic. The term 'mildly basic' would refer to a substance with a pH slightly above 7, and none of the options fit that description.
Step-by-step explanation:
The pH scale is used to determine how acidic or basic a substance is. If a substance has a pH above 7, it is considered basic, whereas substances with a pH below 7 are acidic, and a substance with a pH of exactly 7 is neutral. Among the options given:
- Milk is slightly acidic to neutral (around pH 6.5 to 6.7), not basic.
- Pure water is neutral with a pH of 7.
- Coffee is typically acidic with a pH around 5.
- Vinegar is acidic with a pH around 2 to 3.
Therefore, none of the provided options are known to be mildly basic. However, it should be noted that regular cow's milk is slightly acidic, while milk of magnesia, a different substance used as an antacid and laxative, is indeed basic with a pH of around 10.5. This example serves to illustrate the importance of precise terminology in chemistry. Given the context of the problem, it appears that none of the listed choices would be a correct answer considering the term 'mildly basic.'