Is Matter Around US Pure? Quiz

Centrifugation is a process that involves spinning a mixture at high speeds to separate its components based on their density. In the case of separating butter from curd, centrifugation can be used because butter is less dense than curd. By subjecting the mixture to centrifugal force, the denser curd will settle at the bottom while the lighter butter will rise to the top, allowing for easy separation.

Air is considered a mixture because it is composed of various gases such as nitrogen, oxygen, carbon dioxide, and trace amounts of other gases. These gases are not chemically combined, meaning they can be separated by physical means such as filtration or distillation. Additionally, the composition of air can vary depending on location and environmental factors, further supporting the idea that it is a mixture rather than a compound or element.

Rusting of an article made up of iron is called corrosion. Corrosion is a chemical change because it involves a reaction between iron and oxygen in the presence of water or moisture, leading to the formation of iron oxide (rust). This process is not reversible and results in the degradation and deterioration of the iron article.

Pure substances contain only one kind of particle, meaning that all particles within the substance are the same. This is true for both elements and compounds. Additionally, pure substances have the same composition throughout, meaning that the proportion of different particles remains constant. Therefore, the correct statements are a) and c).

A saturated solution is a solution that has dissolved as much solute as it can at a given temperature. This means that no more solute can be dissolved in the solution without changing the temperature or pressure.

A suspension is a heterogeneous mixture in which solid particles are dispersed in a liquid and can be seen with the naked eye. In the case of sand in water, the sand particles do not dissolve in the water but instead remain suspended, giving the mixture a cloudy appearance. This is different from a true solution, where the solute particles are evenly distributed and cannot be seen, and a colloidal solution, where the solute particles are larger than in a true solution but smaller than in a suspension. Therefore, the correct answer is suspension.

Decaying of wood and burning of wood are both examples of chemical changes. Decaying involves the breakdown of organic matter by microorganisms, resulting in the release of gases and the formation of new compounds. Burning wood involves the rapid oxidation of wood in the presence of oxygen, leading to the production of heat, light, and new substances like ash and smoke. The sawing of wood and the hammering of a nail into a piece of wood, however, are physical changes as they do not involve the formation of new substances or a change in the chemical composition of the wood.

A true solution is a homogeneous mixture where the solute particles are evenly dispersed and cannot be seen with the naked eye. Blood is not a true solution as it contains cells and other particles that can be seen. Milk is also not a true solution as it is a colloidal suspension, meaning it contains larger particles that can be seen under a microscope. Starch solution is not a true solution as it contains suspended starch particles (starch particles are large and do not dissolve completely in water, making starch solutions cloudy). However, sugar solution is a true solution as the sugar molecules are dissolved in the solvent (usually water) and cannot be seen.

Tincture of iodine is a solution that is commonly used as an antiseptic. It is made by dissolving iodine in alcohol and water. Alcohol is used as a solvent because it helps to dissolve the iodine and allows for easy application onto the skin or wounds. The iodine in the tincture acts as an antiseptic by killing or inhibiting the growth of microorganisms, making it an effective solution for disinfection purposes.

A is incorrect because sublimation is the transition from a solid to a gas without passing through the liquid phase.

B is correct because in a crystalline solid, the atoms are indeed arranged in a regular, repeating pattern, which is characteristic of crystalline structures.

C is incorrect because the triple point of a substance is the temperature and pressure at which all three phases (solid, liquid, and gas) coexist in equilibrium.

D is incorrect because deposition is the process where a gas turns directly into a solid, not a liquid.

Milk shows the Tyndall effect because it is a colloidal suspension of fat globules in water. When light passes through milk, the particles scatter the light, making the path of the light visible. This scattering of light is known as the Tyndall effect. Salt solution, copper sulfate solution, and starch solution do not show the Tyndall effect as they do not contain particles large enough to scatter light.

True solutions are homogeneous in nature, meaning that the solute particles are evenly distributed throughout the solvent. They are so small that they cannot be filtered out using filter paper. Additionally, true solutions are stable and do not separate into their individual components over time. However, the statement "At constant temperature, particles of solute settle down" is not true for true solutions. In a true solution, the solute particles are uniformly dispersed and do not settle out, even at constant temperature.

The mass percent concentration of a solution is determined by the mass of the solute present in a given amount of solvent. In this case, the correct answer is 100 gm of solution, as it specifies the amount of solvent (100 gm) in which the solute is dissolved to determine the mass percent concentration.

The correct answer is i, iii and iv. This is because the statement i is correct as P is formed by the combination of X and Y, indicating that it is a compound. The statement iii is correct as X and Y cannot be broken down into simpler substances, indicating that they are elements. The statement iv is correct as P has a fixed composition, meaning that it always contains both X and Y in a specific ratio.

Crystallization is the process by which solid crystals form from a solution, a melt, or sometimes directly from a gas. It typically occurs when the concentration of a substance exceeds its solubility in a liquid, or when a substance cools down and changes from a liquid to a solid state, leading to the arrangement of molecules into a structured, repeating pattern, forming crystals. This process is used in many industrial applications, including the purification of substances and the formation of salts or minerals.