Practice Questions

<ul style="color: rgb(255,255,255);"><li>Standard Voltage: The nominal RMS (Root Mean Square) voltage for domestic power supply in India is standardized at 230V.</li><li>Standard Frequency: The electrical power grid in India operates at a standard frequency of 50Hz (Hertz).</li><li>Tolerance Levels: As per the Indian Electricity Grid Code (IEGC), the permissible variation for voltage is +/- 5% and for frequency is 49.9Hz to 50.05Hz under normal operating conditions.</li><li>AC Power: Domestic supply is delivered as Alternating Current (AC), which is preferred for long-distance transmission due to the efficiency of transformers in stepping voltage up or down.</li><li>Global Context: While India follows the 230V/50Hz standard, many countries in North America (such as the USA and Canada) utilize 110V-120V at 60Hz, making compatibility an important consideration for electronic device design.</li><li>Regulatory Body: The Central Electricity Authority (CEA) under the Ministry of Power is the statutory body responsible for regulating the technical standards for construction of electrical plants and electric lines in India.</li></ul>

<h3 style="color: rgb(255,255,255);">Classification of Electrochemical Cells</h3><ul style="color: rgb(255,255,255);"><li>Primary Cells: These are non-rechargeable cells. Once the chemical energy is exhausted, they cannot be restored to their original state by external electrical energy. Examples include Dry Cell (Leclanché cell), Mercury cell, and Alkaline cell.</li><li>Secondary Cells: These are rechargeable cells. They can be restored to their original state by passing an electric current in the opposite direction to the discharge current (a process known as recharging). Examples include Lead-acid storage battery, Nickel-Cadmium (Ni-Cd) cell, and Lithium-ion (Li-ion) battery.</li></ul><h4 style="color: rgb(255,255,255);">Key Differences for Exams</h4><ol style="color: rgb(255,255,255);"><li>Reversibility: Secondary cells involve reversible chemical reactions, whereas primary cells involve irreversible reactions.</li><li>Usage: Primary cells are commonly used in low-drain devices like remote controls and wall clocks. Secondary cells are used in high-drain devices such as smartphones, laptops, and electric vehicles.</li><li>Cost and Maintenance: Secondary cells have a higher initial cost but are more cost-effective over a long period due to their reusability.</li></ol>Note: A standard Dry Cell is a classic example of a primary cell frequently tested in competitive examinations because it cannot be recharged.

Soaps and detergents both are used only in soft water

Soaps and detergents both are used in soft water as well as hard water

Soap is used only in soft water while detergent can be used in soft water as well as hard water

Detergent is used only in soft water while soap is used in soft water and hard water both

<h3 style="color: rgb(255,255,255);">Composition of LPG</h3><ul style="color: rgb(255,255,255);"><li>Liquefied Petroleum Gas (LPG) is primarily a mixture of flammable hydrocarbon gases, specifically Propane (C3H8) and Butane (C4H10).</li><li>In some regions, it may contain smaller proportions of Propylene or Butylene depending on the production process and the specific market standards.</li><li>LPG is a fossil fuel byproduct obtained during the refining of petroleum or extracted from natural gas streams.</li></ul><h4 style="color: rgb(255,255,255);">Key Characteristics</h4><ul style="color: rgb(255,255,255);"><li>State: Under normal atmospheric pressure, these gases exist as vapors; however, they are stored as liquids under moderate pressure in steel cylinders to reduce volume.</li><li>Odorization: Because LPG is naturally odorless, Ethyl Mercaptan is added as an odorant to ensure leaks can be detected by smell, serving as a critical safety measure against fire and explosion hazards.</li><li>Combustion: It is a high-calorific value fuel that burns cleanly, producing fewer particulates and lower levels of carbon monoxide compared to traditional solid fuels.</li><li>Density: LPG vapor is heavier than air, meaning that in the event of a leak, it tends to accumulate in low-lying areas or floor-level crevices, which is a vital factor in fire hazard mitigation and ventilation design.</li></ul>

<ul style="color: rgb(255,255,255);"><li>Minamata Disease: It is a neurological syndrome caused by severe mercury poisoning. It is not an infectious disease but rather a toxicological condition resulting from environmental contamination.</li><li>Origin: The disease was first discovered in Minamata City, Kumamoto Prefecture, Japan, in 1956. It was caused by the release of methylmercury into the wastewater from the Chisso Corporation's chemical factory.</li><li>Transmission: The mercury bioaccumulated in shellfish and fish in Minamata Bay, which, when consumed by the local population, led to severe mercury poisoning.</li><li>Health Impact: Mercury is a potent neurotoxin. Symptoms include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision, and damage to hearing and speech. In extreme cases, it leads to insanity, paralysis, coma, and death. It primarily targets the central nervous system.</li><li>Comparison with other diseases: <ul style="color: rgb(255,255,255);"><li>Itai-itai disease: Caused by the ingestion of cadmium, primarily affecting bones and the kidneys.</li><li>Lead poisoning: Often associated with anemia, hypertension, and developmental issues, but not specifically linked to the Minamata incident.</li></ul></li></ul>

It was caused by consumption of fish containing lead.

It was caused by consumption of fish containing mercury.

It was caused by consumption of fish containing cadmium.

<ul style="color: rgb(255,255,255);"><li>Hydrogen Peroxide (H2O2) is widely recognized as a green solvent or an environmentally friendly bleaching agent.</li><li>Mechanism of Action: It functions through the process of oxidation. Upon decomposition, it releases nascent oxygen, which effectively breaks down the chromophores (color-causing molecules) in stains and fabrics, turning them into colorless substances.</li><li>Environmental Impact: Unlike chlorine-based bleaches, Hydrogen Peroxide leaves behind only water and oxygen as byproducts, making it non-toxic and biodegradable.</li><li>Industrial Application: It is frequently referred to as an environmentally benign bleaching agent in the textile and paper pulp industries.</li><li>Safety and Stability: It is safer for fabric fibers compared to harsh chemical bleaches, though its efficacy depends heavily on the concentration and pH level of the solution.</li><li>Chemical Properties: It is a strong oxidizing agent that is stable in acidic conditions but decomposes rapidly in the presence of catalysts or alkaline environments.</li></ul>

<h3 style="color: rgb(255,255,255);">പ്രകാശത്തിന്റെ അപവർത്തനം (Refraction)</h3><ul style="color: rgb(255,255,255);"><li>ഒരു മാധ്യമത്തിൽ നിന്നുള്ള പ്രകാശത്തിന്റെ പ്രവേഗവും (Velocity) അപവർത്തനാങ്കവും (Refractive Index) തമ്മിലുള്ള ബന്ധം താഴെ പറയുന്ന സൂത്രവാക്യം ഉപയോഗിച്ച് കണ്ടെത്താം: n1v1 = n2v2</li><li>ഇവിടെ:<ul style="color: rgb(255,255,255);"><li>n1 = ഒന്നാമത്തെ മാധ്യമത്തിന്റെ അപവർത്തനാങ്കം (1.5)</li><li>v1 = ഒന്നാമത്തെ മാധ്യമത്തിലെ പ്രകാശത്തിന്റെ പ്രവേഗം (2 x 10^8 m/s)</li><li>n2 = രണ്ടാമത്തെ മാധ്യമത്തിന്റെ അപവർത്തനാങ്കം (1.6)</li><li>v2 = രണ്ടാമത്തെ മാധ്യമത്തിലെ പ്രകാശത്തിന്റെ പ്രവേഗം (കണ്ടെത്തേണ്ടത്)</li></ul></li></ul><h4 style="color: rgb(255,255,255);">കണക്കുകൂട്ടൽ:</h4><ol style="color: rgb(255,255,255);"><li>n1v1 = n2v2 എന്നതിൽ വിലകൾ ചേർക്കുക: 1.5 x (2 x 10^8) = 1.6 x v2</li><li>3 x 10^8 = 1.6 x v2</li><li>v2 = (3 x 10^8) / 1.6</li><li>v2 = 1.875 x 10^8 m/s</li></ol><ul style="color: rgb(255,255,255);"><li>പ്രധാന വസ്തുതകൾ: പ്രകാശത്തിന്റെ പ്രവേഗം ഒരു മാധ്യമത്തിന്റെ അപവർത്തനാങ്കത്തിന് വിപരീതാനുപാതത്തിലാണ് (Inversely proportional). അതിനാൽ, അപവർത്തനാങ്കം കൂടുമ്പോൾ പ്രകാശത്തിന്റെ പ്രവേഗം കുറയുന്നു.</li><li>വാക്വത്തിൽ പ്രകാശത്തിന്റെ പ്രവേഗം ഏകദേശം 3 x 10^8 m/s ആണ്.</li><li>അപവർത്തനാങ്കത്തിന് യൂണിറ്റുകൾ ഇല്ല (Unitless quantity).</li></ul>

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