6. Milk, pure water, lemon juice, and gastric juice were tested using a pH meter. Results are summarized in the chart below. Which substance is the most acidic?
Answer: A
Gastric juice is the most acidic substance tested.
Gastric juice has the lowest pH value among the substances tested, indicating that it is the most acidic. This is characteristic of gastric juice, which contains hydrochloric acid and plays a vital role in digestion.
A) Gastric juice
Gastric juice is known for its highly acidic nature due to the presence of hydrochloric acid, which typically results in a pH level around 1.5 to 3.5. This low pH confirms that gastric juice is indeed the most acidic substance in the provided comparison.
B) Milk
Milk generally has a pH level ranging from 6 to 7, making it slightly acidic to neutral. While it is more acidic than pure water, it does not approach the acidity level of gastric juice, thus it is not the most acidic option.
C) Pure water
Pure water has a neutral pH of 7. This neutrality makes it less acidic compared to gastric juice and other substances. Therefore, pure water cannot be considered the most acidic.
D) Lemon juice
Lemon juice is acidic, with a pH typically around 2 to 3. While it is more acidic than milk and pure water, it is still less acidic than gastric juice, which has a lower pH value. Thus, lemon juice is not the most acidic substance tested.
Conclusion
Gastric juice is definitively the most acidic substance among the options due to its significantly lower pH level compared to milk, pure water, and lemon juice. Each of the other substances exhibits a higher pH, confirming that they are less acidic than gastric juice.