Which one among the following substances is a compound?
Sugar
Understanding Compounds and Mixtures
The question asks us to identify which of the given substances is a compound. To answer this, we need to understand the difference between pure substances (elements and compounds) and mixtures.
What is a Compound?
A compound is a pure substance formed when two or more different chemical elements are chemically bonded together in a fixed ratio. For example, water (\(\text{H}_2\text{O}\)) is a compound because it is formed from hydrogen and oxygen atoms chemically bonded in a fixed 2:1 ratio.
What is a Mixture?
A mixture is a substance comprising two or more components (elements or compounds) that are not chemically bonded. The components in a mixture retain their individual properties and can often be separated by physical means. Mixtures have variable composition.
Analyzing the Options
Let's examine each option provided:
- Sugar: Common table sugar is sucrose. Its chemical formula is \(\text{C}_{12}\text{H}_{22}\text{O}_{11}\). This means it is formed from carbon, hydrogen, and oxygen atoms chemically bonded in a fixed ratio. Therefore, sugar (sucrose) is a chemical compound.
- Air: Air is primarily a mixture of gases like nitrogen (\(\text{N}_2\)), oxygen (\(\text{O}_2\)), argon (\(\text{Ar}\)), carbon dioxide (\(\text{CO}_2\)), and trace amounts of other gases. These components are not chemically bonded, and their proportions can vary slightly depending on location and altitude. Air is a mixture.
- Milk: Milk is a complex mixture containing water, fats, proteins (like casein and whey), carbohydrates (like lactose), minerals, and vitamins. These components are not chemically bonded together as a single substance. Milk is a mixture.
- Tea: Tea is typically prepared by infusing tea leaves in hot water. It is a solution (a type of homogeneous mixture) containing water and various compounds extracted from the tea leaves, such as caffeine, tannins, and flavorings. The composition varies depending on the type of tea and how it is brewed. Tea is a mixture.
Based on these definitions and analyses, sugar (sucrose) fits the description of a chemical compound because it has a fixed chemical composition with elements chemically bonded together.
| Substance | Classification | Reason |
|---|---|---|
| Sugar (Sucrose) | Compound | Fixed chemical formula (\(\text{C}_{12}\text{H}_{22}\text{O}_{11}\)), elements chemically bonded. |
| Air | Mixture | Variable composition, components not chemically bonded (e.g., \(\text{N}_2\), \(\text{O}_2\)). |
| Milk | Mixture | Variable composition, various components not chemically bonded (water, fats, proteins, etc.). |
| Tea | Mixture | Variable composition, components not chemically bonded (water + extracted compounds). |
Therefore, among the given options, sugar is the substance that is classified as a compound.
Revision Table: Pure Substances vs. Mixtures
| Feature | Pure Substance | Mixture |
|---|---|---|
| Composition | Fixed and uniform | Variable |
| Components | One type of particle (element or compound) | Two or more substances physically combined |
| Separation | Cannot be separated by physical means | Can often be separated by physical means |
| Properties | Specific set of properties | Properties are the average of its components |
| Examples | Iron, Water, Sugar (\(\text{C}_{12}\text{H}_{22}\text{O}_{11}\)) | Air, Saltwater, Sand and Iron filings |
Additional Information: Classification of Matter
Matter can be broadly classified into pure substances and mixtures.
- Pure Substances: Have a definite and constant composition.
- Elements: Pure substances made up of only one type of atom (e.g., Gold (\(\text{Au}\)), Oxygen (\(\text{O}_2\)), Iron (\(\text{Fe}\))).
- Compounds: Pure substances made up of two or more different elements chemically bonded together in a fixed proportion (e.g., Water (\(\text{H}_2\text{O}\)), Carbon Dioxide (\(\text{CO}_2\)), Sugar (\(\text{C}_{12}\text{H}_{22}\text{O}_{11}\))).
- Mixtures: Consist of two or more substances physically combined in variable proportions.
- Homogeneous Mixtures: Have uniform composition throughout (e.g., Saltwater, Air, alloys like Brass).
- Heterogeneous Mixtures: Have non-uniform composition, and the components are often visible (e.g., Sand and water, Oil and water, Salad).
Understanding this classification helps distinguish between different types of matter found around us, like sugar, air, milk, and tea.
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Select the correct answer using the code given below.
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