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Ideal Gas Equation Explained: PV = nRT, Units, Forms, and JEE Tips [2025 Guide]

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  📌 Ideal Gas Equation: A Complete Guide for JEE & NEET Aspirants The Ideal Gas Equation , one of the most essential and frequently used equations in physics and chemistry, connects pressure , volume , temperature , and moles of gas into one compact relationship: 👉 The Equation: PV = nRT Where: P = Pressure V = Volume n = Number of moles R = Universal gas constant T = Temperature (in Kelvin) Let’s dive deep into this equation, understand each part, know when to use which form, and crack tricky numerical problems easily in JEE, NEET, NDA, or Class 11-12 Boards . 🔍 Understanding Each Term in PV = nRT ✅ P — Pressure Unit: atm or Pascal (Pa) 1 atm = 1.013 × 10⁵ Pa Represents the force gas molecules exert on the container walls. ✅ V — Volume Unit: Litres (L) or cubic meters (m³) 1 L = 10⁻³ m³ The space occupied by gas. ✅ n — Number of Moles n = mass / molar mass Represents how many moles (or molecules) of gas are presen...
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Balanced Redox Reaction: Mg + HNO₃ → Mg(NO₃)₂ + N₂O + H₂O | JEE Chemistry

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  ⚗️ Balance the Equation: Mg + HNO₃ ⟶ Mg(NO₃)₂ + N₂O + H₂O ❓ Question: Balance the following chemical equation: Mg + HNO₃ ⟶ Mg(NO₃)₂ + N₂O + H₂O This question appears simple at first glance, but it actually requires deep understanding of redox reactions and balancing complex equations . 🎯 Key Concepts Tested: Oxidation and reduction processes Balancing redox equations using ion-electron method or oxidation number method Conservation of mass and conservation of charge Identifying oxidizing and reducing agents Understanding product formation in acidic medium (presence of HNO₃) 🧠 Step-by-Step Solution Strategy: Step 1: Identify oxidation states Let’s determine oxidation states of all elements in reactants and products: Mg (0) → Mg²⁺ in Mg(NO₃)₂ → Oxidation (Mg is losing electrons) N in HNO₃: +5 N in N₂O: +1 → Reduction (N is gaining electrons) Step 2: Write unbalanced half-reactions Oxidation (Mg): Mg → Mg²⁺ + 2e⁻ Reduction (N): 2...
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Centroid of Circular Disc with Hole | System of Particles | JEE Physics | Doubtify JEE

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🌀 Centroid of a Circular Plate with a Hole | System of Particles | JEE Physics | Doubtify JEE ❓ Question: A circular hole of radius (a/2) is cut out of a circular disc of radius ‘a’ , as shown in the figure. What will be the position of the centroid of the remaining circular portion with respect to point ‘O’ ? 🖼️ Question Image: 🧠 Solution Image: ✍️ Detailed Explanation: To solve this problem, we apply the concept of mass moment (or area moment) . When a portion is cut out from a symmetric object, we use the principle of superposition — treat the hole as a negative mass or negative area. Let’s break it down: 🧮 Step 1: Assume mass per unit area = σ Area of full disc = πa² Area of hole = π(a/2)² = (πa²)/4 Remaining area = πa² – (πa²)/4 = (3πa²)/4 🧮 Step 2: Find centroid of each part Full disc’s centroid = At origin (O) Hole’s centroid is at a distance of a/2 from O along the radius. 🧮 Step 3: Apply formula for center of mass (COM): Let x be the position of the c...
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