Modern ABC Chemistry Class 12

Explanation: This question asks about the chemical nature of nylon by identifying the category of polymer it belongs to based on its structure and composition. Polymers are large molecules formed by repeating smaller units called monomers, and their classification depends on the type of linkage present between these units. Some Polymers contain simple carbon chains, while others include functional groups such as amide or ester linkages. Nylon is a synthetic fiber widely used in textiles and engineering plastics due to its strength and elasticity. It is formed through a condensation polymerization process where monomers combine with the elimination of small molecules like water. The structure of nylon contains specific linkages that determine its classification among Polymers. For example, Polymers with ester linkages differ significantly in properties from those with amide linkages. Understanding the type of bond present in the polymer chain helps identify its category. Just like identifying a fabric based on its weave or thread type, recognizing the linkage in a polymer helps determine what kind of material it is. In summary, nylon is categorized based on the type of repeating chemical linkage formed during its synthesis process.

Explanation: This question focuses on identifying the scientific method used to obtain pure water by removing dissolved or suspended impurities. In Chemistry, separation techniques are used to isolate substances based on differences in physical properties such as boiling point, solubility, or particle size. When water contains impurities, simply filtering may not remove dissolved substances, so more advanced methods are required. One common technique involves heating the impure liquid until it turns into vapor and then cooling that vapor back into liquid form. During this process, non-volatile impurities remain behind while the vapor condenses into pure liquid. This method relies on differences in boiling points and the ability of substances to change states. It is widely used in laboratories and industries to purify liquids. A simple analogy is collecting steam from boiling water and condensing it back into clean water, leaving Salts or other impurities behind in the container. Overall, the process is based on phase change and selective separation, ensuring that only the pure component is collected after condensation.

Explanation: This question examines the various applications of a strong mineral Acid and asks which role is not appropriate for it based on its chemical behavior. Sulphuric Acid is known for its strong acidic nature, high affinity for water, and ability to remove moisture from substances. It is commonly used in industrial processes, laboratories, and chemical reactions where dehydration or drying is required. Additionally, its reactivity allows it to act as a powerful agent in removing water molecules from compounds. However, not all applications are suitable due to its highly corrosive and toxic nature. Substances used in Food or biological contexts must meet safety standards and should not pose harm when consumed or contacted. Since sulphuric Acid is extremely reactive and can cause severe damage to living tissues, its use is restricted in certain areas. Just as cleaning chemicals are effective for surfaces but unsafe for ingestion, chemical properties determine safe and unsafe applications. Thus, evaluating its chemical characteristics helps identify where it cannot be used.

Explanation: This question focuses on identifying a common gaseous component shared by two different fuel sources. Natural gas is a fossil fuel found deep underground, while biogas is produced through the decomposition of Organic Matter by microorganisms in the absence of oxygen. Despite their different origins, both gases are used as fuel because they release energy upon combustion. The composition of these gases includes various Hydrocarbons and other minor components. A key similarity lies in the presence of a simple hydrocarbon that is highly combustible and efficient as an energy source. This gas is formed both naturally in geological processes and biologically during the breakdown of Organic waste. For example, when Food waste or Animal dung decomposes in a sealed Environment, this gas is produced and can be collected for use. Similarly, it forms a major portion of fossil fuel reserves. In summary, the shared gas is identified by its energy-rich nature and its formation in both natural and biological processes.

Explanation: This question deals with the structure of the Periodic Table, specifically the arrangement of elements in horizontal rows called periods. Each period represents a new principal energy level where electrons are added to atomic orbitals. The number of elements in a period depends on how many orbitals are available for electron filling in that energy level. The second period begins after the first, which contains very few elements due to limited orbital availability. In the second period, electrons fill the 2s and 2p orbitals, which together can accommodate a specific number of electrons. Since each element corresponds to the addition of one electron, counting the total capacity of these orbitals gives the number of elements in that period. For instance, s orbitals can hold two electrons, while p orbitals can hold six. Adding these capacities provides the total number of positions available. This determines how many distinct elements appear in that row. Overall, understanding orbital structure helps determine the size of each period in the Periodic Table.

Explanation: This question asks about the chemical compound responsible for the sensation of Heat experienced when consuming certain spicy foods. The “hotness” or pungency of peppers is not related to temperature but to a chemical interaction with sensory receptors in the human body. Certain compounds can stimulate nerve endings, particularly those that detect Heat and pain, creating a burning sensation. This compound is found mainly in the inner tissues of peppers and varies in concentration depending on the type of pepper. When consumed, it binds to receptors in the mouth and triggers a signal similar to that caused by actual Heat. This is why spicy Food feels hot even though its temperature may be normal. A useful analogy is how menthol in mint creates a cooling sensation without lowering temperature; similarly, this compound creates a Heat-like effect. In summary, the perceived spiciness is due to a specific chemical that interacts with sensory receptors rather than actual thermal Heat.

Explanation: This question explores substances used in medicine to reduce pain or induce unconsciousness during surgical procedures and asks which one does not serve this purpose. Anesthetic agents are chemicals that affect the nervous system to block pain sensations or render a patient unconscious temporarily. These substances must be carefully selected to ensure safety, effectiveness, and controlled action. Common anesthetics include gases and liquids that depress brain activity or interfere with nerve signal transmission. However, not all chemical substances have such effects on the human body. Some compounds are commonly used as solvents or in industrial applications and do not possess properties that influence the nervous system in the required way. For example, a substance used to dissolve paints or clean surfaces may not have any anesthetic effect. Just as not every liquid medicine can relieve pain, only specific compounds are suitable for anesthesia. Thus, identifying their function and application helps distinguish which substance is not used in surgical anesthesia.

Explanation: This question tests the understanding of a commonly used term in Chemistry and everyday life related to solutions. A solution is formed when a solute dissolves in a solvent, creating a uniform mixture. In many cases, water acts as the solvent, and various substances can dissolve in it depending on their nature. Brine is a term used to describe a particular type of solution that is widely used in Food preservation, chemical industries, and cooling systems. It involves dissolving a specific substance in water to form a concentrated mixture. This solution has properties such as higher density and lower freezing point compared to pure water, making it useful in various applications. For example, preserving pickles or curing Food often involves immersing them in such a solution to prevent spoilage. Just like sugar dissolves in water to form a sweet solution, certain other substances dissolve to form brine. In summary, brine is defined by the type of solute dissolved in water and its resulting properties.