Identify the pure substances and mixture from the following list : (a) solid common salt (b) milk (c) air (d) oxygen (e) fruit juice (f) brass (g) copper sulphate crystals (h) distilled water (i) sugar solution (j) honey (k) Ice cream (l) Iron sulphide
The Correct Answer and Explanation is:
Here’s the classification of each substance from the list:
Pure Substances:
- Solid Common Salt (a) – This is a pure substance. It is made up entirely of sodium chloride (NaCl) and does not contain any other components. The composition is uniform throughout.
- Oxygen (d) – Oxygen is a pure substance. It consists only of O₂ molecules and has a consistent composition.
- Copper Sulphate Crystals (g) – Copper sulfate (CuSO₄) in its solid form is a pure substance because it is made up of a specific chemical compound in a uniform structure.
- Distilled Water (h) – Distilled water is a pure substance. It contains only H₂O molecules and has been purified of any impurities or solutes.
Mixtures:
- Milk (b) – Milk is a mixture. It contains water, fats, proteins, lactose, and minerals, all combined together but not chemically bonded. It is a heterogeneous mixture.
- Air (c) – Air is a mixture. It is made up of several gases, primarily nitrogen, oxygen, carbon dioxide, and other trace gases, which are physically mixed but not chemically bonded.
- Fruit Juice (e) – Fruit juice is a mixture. It consists of water, sugars, vitamins, and other components from fruit, combined together but not chemically bound.
- Brass (f) – Brass is an alloy mixture, primarily made of copper and zinc. The two metals are physically mixed together but are not chemically bonded.
- Sugar Solution (i) – A sugar solution is a mixture. It consists of sugar (sucrose) dissolved in water. The sugar can be physically separated from the water, indicating it’s a mixture.
- Honey (j) – Honey is a mixture. It is made up of water, sugars, enzymes, and other compounds. These components are mixed but not chemically bonded.
- Ice Cream (k) – Ice cream is a mixture. It is a combination of water, fats, sugars, proteins, and air that are physically mixed together.
- Iron Sulphide (l) – Iron sulfide (FeS) is a pure substance when it is in its solid form. However, if it is mixed with other components, it could become a mixture. Pure iron sulfide is a compound, a specific chemical combination of iron and sulfur.
Conclusion:
- Pure substances: Solid common salt, oxygen, copper sulfate crystals, distilled water.
- Mixtures: Milk, air, fruit juice, brass, sugar solution, honey, ice cream.
Pure substances have a fixed composition, while mixtures contain two or more substances that are physically combined.
