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Past Year Paper, Chemistry (Set - 3), Outside Delhi, 2014, Class 12, Chemistry | Additional Study Material for Class 12 PDF Download

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FAQs on Past Year Paper, Chemistry (Set - 3), Outside Delhi, 2014, Class 12, Chemistry - Additional Study Material for Class 12

1. What are the physical properties of water?
Ans. Water is a colorless and odorless liquid that exists in three states: solid (ice), liquid, and gas (water vapor). It has a high boiling point (100°C) and melting point (0°C) compared to other similar-sized molecules due to its hydrogen bonding. Additionally, water has a high heat capacity, meaning it can absorb and store a large amount of heat energy without experiencing a significant increase in temperature.
2. How does water dissolve substances?
Ans. Water is known as the "universal solvent" because it has the ability to dissolve a wide variety of substances. This is due to its polar nature. Water molecules consist of two hydrogen atoms covalently bonded to an oxygen atom, with the oxygen atom being slightly negatively charged and the hydrogen atoms being slightly positively charged. When a substance is dissolved in water, the polar water molecules surround the charged particles of the substance, causing them to separate and disperse throughout the water, resulting in a homogeneous mixture.
3. What is the pH scale and how does it measure acidity or alkalinity?
Ans. The pH scale is a measurement scale used to determine the acidity or alkalinity of a substance. It ranges from 0 to 14, with 7 being considered neutral. A pH value below 7 indicates acidity, while a value above 7 indicates alkalinity. The pH scale is logarithmic, meaning that each unit represents a tenfold difference in acidity or alkalinity. pH is determined by the concentration of hydrogen ions (H+) in a solution. A higher concentration of H+ ions results in a lower pH value, indicating greater acidity, while a lower concentration of H+ ions results in a higher pH value, indicating greater alkalinity.
4. How does water exhibit surface tension?
Ans. Surface tension is a property of liquids that allows them to resist external forces and minimize their surface area. Water exhibits surface tension due to the cohesive forces between its molecules. The hydrogen bonds between water molecules create an attraction that pulls the molecules at the surface inward, resulting in a surface film that behaves like a stretched elastic sheet. This cohesive force gives water its ability to form droplets and allows small insects to walk on water.
5. What are the chemical reactions involved in water?
Ans. Water can undergo a variety of chemical reactions. One of the most important reactions is the self-ionization of water, where water molecules can transfer a proton (H+) between each other, resulting in the formation of hydronium ions (H3O+) and hydroxide ions (OH-). This reaction is responsible for the concept of pH and the acidity or alkalinity of a solution. Water can also participate in acid-base reactions, oxidation-reduction reactions, and hydrolysis reactions, among others. These reactions play crucial roles in various biological and chemical processes.
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