Doubtify – JEE Ki Taiyaari, Simple Bhasha Mein

  ⚛️ Bohr’s Atomic Model in 59 Seconds | Doubtify JEE Shorts 📌 Question: What explains the fixed energy levels of electrons in an atom and why do atoms emit light? Bohr’s Atomic Model gives us the first quantum explanation of atomic structure! 📸 Image: 📕 Concept & Formula: Stationary Orbits: Electrons revolve around the nucleus in fixed circular paths called orbits. No radiation is emitted in these orbits. Quantized Angular Momentum: m v r = n h 2 π mvr = \frac{nh}{2\pi} Where: m = mass , v = velocity , r = radius , n = orbit number (1, 2, 3…) , h = Planck's constant Energy Transitions: When an electron jumps between orbits: Δ E = E 2 − E 1 = h ν \Delta E = E_2 - E_1 = h\nu Energy is absorbed or emitted in the form of light/spectral lines Energy of Orbit: E n ∝ − 1 n 2 E_n \propto -\frac{1}{n^2} → Lower orbit → More negative energy → More stability 🔢 Example: An electron jumps from n = 3 to n = 2 , and emits energy. This corre...

  🧪 Young’s Modulus from Wire Extension | JEE Physics | Doubtify 📌 Question: A 3 m long wire of radius 3 mm shows an extension of 0.1 mm when loaded vertically by a mass of 50 kg in an experiment to determine Young's modulus. The value of Young’s modulus of the wire as per this experiment is P × 10¹¹ N/m² , where the value of P is: (Take g = 3π m/s²) 🖼️ Question Image:

  🔥 Adiabatic Compression of Monatomic Gas | Thermodynamics | JEE Physics | Doubtify 📌 Question: A monatomic gas having γ = 5 3 \gamma = \frac{5}{3} ​ is stored in a thermally insulated container , and the gas is suddenly compressed to 1 8 th \frac{1}{8}^\text{th} of its initial volume. What is the ratio of final pressure to initial pressure ? 🖼️ Question Image:

  ⚡ Surface Charge Distribution on Irregular Conductor – Electrostatics | JEE Physics | Doubtify JEE 📌 Question: Electric charge is transferred to an irregular metallic disk as shown in the figure. If the surface charge densities at four points are σ₁, σ₂, σ₃, and σ₄ , then which of the following options is correct ?

  ⚡ Surface Charge Density After Contact – Electrostatics | JEE Physics | Doubtify JEE 📌 Question: Two metal spheres of radius R and 3R have the same surface charge density σ . They are brought in contact and then separated . After separation, let the surface charge densities be σ₁ (for smaller sphere) and σ₂ (for larger sphere). What is the ratio σ₁ / σ₂ ? 🖼️ Question Image:

  🏐 Momentum vs Height Graph – Vertical Motion | JEE Physics | Doubtify JEE 📌 Question: A ball is thrown vertically upwards (take +z-axis as upwards) from the ground. 👉 Which of the following momentum-height (p–h) graphs correctly represents the motion? This is a concept-based question that checks your understanding of vector momentum and energy conservation . 🖼️ Question Image:

  🚀 Uniform Acceleration Motion Graphs | Kinematics | Doubtify JEE 📌 Question: A particle starts from origin O from rest and moves with a uniform acceleration along the positive x-axis . 👉 Identify all the graphs that correctly represent the motion qualitatively: a = acceleration v = velocity x = displacement t = time This is a conceptual question testing your understanding of motion graphs! 🖼️ Question Image:

  🧭 Relative Motion of Ships – Minimum Distance Concept | JEE Physics | Doubtify JEE 📌 Question: Ship A is sailing towards north-east with velocity v = 30 î + 50 ĵ km/h , where î points east and ĵ points north . Ship B is at a distance of 80 km east and 150 km north of Ship A and is sailing west at 10 km/h . 🔍 Find the time at which Ship A is at minimum distance from Ship B. 🖼️ Question Image:

  🚢 Minimum Distance Between Two Moving Ships – Relative Motion | JEE Physics | Doubtify JEE 💡 Question: Ship A is sailing towards the north-east with velocity v = 30 î + 50 ĵ km/h , where î points east and ĵ points north . Ship B is located at a distance of 80 km east and 150 km north of ship A and is sailing towards the west at 10 km/h . Question: After how much time will Ship A be at a minimum distance from Ship B ? 🖼️ Question Image:

  🔢 Matrices & Determinants | JEE Maths | Doubtify JEE 📌 Question: The number of all 3 × 3 matrices A , with entries from the set {-1, 0, 1} , such that the sum of the diagonal elements of AAᵀ is 3 , is: 🖼️ Question Image:

  📈 Acceleration as a Function of Distance – Motion in One Dimension | JEE Physics | Doubtify JEE 🧮 Question: The distance x covered by a particle in one-dimensional motion varies with time t as: x² = at² + 2bt + c . If the acceleration of the particle depends on x as x⁻ⁿ , where n is an integer, what is the value of n ? 🖼️ Question Image: ✅ Detailed Concept & Solution: This is a JEE-level conceptual problem involving the relation between distance, velocity, and acceleration — with a twist of functional dependence. We are given: x² = at² + 2bt + c — (1) To find acceleration and its dependency on x , let’s differentiate both sides of equation (1): Differentiate w.r.t. time t : 2x(dx/dt) = 2at + 2b ⇒ v = dx/dt = (at + b)/x — (2) Now differentiate velocity v w.r.t time to find acceleration: a = dv/dt = d/dt[(at + b)/x] Use quotient rule: a = [a·x - (at + b)(dx/dt)] / x² Plug dx/dt = (at + b)/x from (2): a = [a·x - (at + b)·((at + b)/x)] / x² ⇒ ...

  ⏱️ Acceleration-Time Graph – Find Time When Initial Velocity is Regained | JEE Physics | Doubtify JEE ❓ Question: The acceleration-time graph of a particle is as shown. At what time does the particle acquire its initial velocity again?

🔄 Circular Motion | Physics | Doubtify JEE

🧪 Question: The ratio of mass percent of C and H of an organic compound (CxHyOz) is 6:1. If one molecule of the above compound contains half as much oxygen as required to burn one molecule of compound CxHy completely to CO₂ and H₂O, then what is the empirical formula of the compound? 📌 Why This Question is Important: This question combines two highly testable concepts in JEE Chemistry – combustion analysis and empirical formula derivation . You’re not only working with mass percent ratio , but also applying oxygen balancing logic in a combustion reaction. Such questions are frequently seen in organic chemistry chapters , particularly under Basic Principles of Organic Chemistry and Stoichiometry . Mastering this helps you crack more complex analysis-based questions in JEE Mains and even Advanced . 💡 Concept Used: To find the empirical formula , we first convert the mass percent ratio of C and H into moles , assuming 100 g of substance. Then we apply a stoichiometric appr...

🧪 Kinematics – Motion in a Straight Line | Physics | JEE Mains 📌 Question: A stone is dropped from the top of a building.  When it crosses a point 5 m below the top , another stone starts to fall from a point 25 m below the top , and both stones reach the bottom of the building simultaneously . Find the height of the building . (Take g = 10 m/s²) 🖼️ Question Image: 🧠 Solution (Image): 🎥 Video Solution: 🔍 Why this Question is Important: This is a  classic conceptual question from Kinematics , commonly asked in  JEE Mains  and other engineering entrance exams. It checks your understanding of  relative motion ,  free fall , and  time equations of motion  – topics that are often mixed to form trick questions. 📩 Have a Doubt? Drop us a mail at  doubtifyqueries@gmail.com  or DM us on  Instagram . Stay consistent. Watch – Pause – Solve – Repeat. Team Doubtify is with you till the finish line! 💪

  🧪 Balance the Ionic Equation in Alkaline Medium: Cr(OH)₃ + IO₃⁻ → I⁻ + CrO₄²⁻ | Doubtify JEE 📌 Question: Balance the following ionic equation in alkaline medium : Cr(OH)₃ + IO₃⁻ → I⁻ + CrO₄²⁻ 🖼️ Question Image: 🧠 Solution (Image): 🎥 Video Solution: 🔍 Why this Question is Important: This is a frequently asked question from Redox Reactions , commonly seen in JEE Mains and Advanced exams. Knowing how to balance redox reactions in alkaline medium is a core skill every aspirant must master. 📩 Have a Doubt? Drop us a mail at doubtifyqueries@gmail.com or DM us on Instagram . Stay consistent. Watch – Pause – Solve – Repeat. Team Doubtify is with you till the finish line! 💪