Which of the following is not a mixture? A. antibiotic B. Evaporated milk C. brewed coffee D. Hydrogen chloride
Which of the following is not a mixture? A. antibiotic B. Evaporated milk C. brewed coffee D. Hydrogen chloride
The Correct Answer and Explanation is:
Correct Answer: D. Hydrogen chloride
Explanation:
A mixture is a combination of two or more substances where each substance retains its own chemical identity and properties. Mixtures can be homogeneous (uniform composition throughout, like saltwater) or heterogeneous (non-uniform composition, like salad). In contrast, a pure substance has a uniform and definite composition. Pure substances can be elements (like oxygen) or compounds (like water, H₂O).
Now, let’s examine each option:
- A. Antibiotic
Antibiotics, such as amoxicillin or penicillin, are often dispensed in formulations that contain active pharmaceutical ingredients (APIs) mixed with binders, fillers, and other inactive components. As such, commercially available antibiotics are mixtures of various chemical substances. - B. Evaporated milk
Evaporated milk is made by removing about 60% of the water from regular milk. It still contains fats, proteins, sugars (like lactose), and minerals. Because it contains various compounds not chemically bonded together, it is a homogeneous mixture. - C. Brewed coffee
Brewed coffee is an aqueous solution containing hundreds of different dissolved substances (e.g., caffeine, oils, acids). It is a mixture, particularly a homogeneous one if filtered, though it may be heterogeneous if unfiltered (e.g., with coffee grounds). - D. Hydrogen chloride (HCl)
Hydrogen chloride is a pure compound, composed of hydrogen and chlorine atoms chemically bonded in a 1:1 ratio. It has a fixed chemical formula (HCl) and specific properties. It is not a mixture, but a compound.
Conclusion:
Among the options, only hydrogen chloride is a pure substance and not a mixture. Therefore, option D is the correct answer.
