Past Paper Solutions | NEET JEEnius AI Blog

Past Paper Solutions

Immunity NEET 2026: Secondary Lymphoid Organs Explained

Tonsils and spleen are secondary lymphoid organs; use the NCERT development-versus-response rule to distinguish them from bone marrow and thymus.

Founder, JEEnius - IIT Kanpur Alumni · Sep 19, 2026 · 4 min read

Past Paper Solutions

Chemical Thermodynamics NEET 2014: Silver Carbonate Ksp

Solve the NEET 2014 silver carbonate question using standard Gibbs energy, correct unit conversions and the natural-log relation.

Founder, JEEnius - IIT Kanpur Alumni · Sep 19, 2026 · 4 min read

Past Paper Solutions

Rotational Motion NEET 2010: Two-Disc Energy Loss

Work through the two-disc solution to obtain option D, separate frictional dissipation from the first disc’s energy decrease, and check the result with practice questions.

Founder, JEEnius - IIT Kanpur Alumni · Sep 19, 2026 · 5 min read

Past Paper Solutions

PCR and Selectable Markers NEET 2026: Plasmid Question

Understand why both plasmid statements are true, avoid the chromosomal-integration trap, and distinguish PCR amplification from antibiotic selection.

Founder, JEEnius - IIT Kanpur Alumni · Sep 18, 2026 · 4 min read

Past Paper Solutions

D- and f-Block Elements NEET 2008: Second Ionization Order

Learn why second ionization enthalpy follows Cr > Mn > V > Ti by comparing the singly charged ions.

Founder, JEEnius - IIT Kanpur Alumni · Sep 18, 2026 · 4 min read

Past Paper Solutions

Gravitation NEET 2011: When Is Gravitational Power Greatest?

Gravity supplies its greatest signed power just before return to Earth's surface; the force-velocity direction check explains why option A is correct.

Founder, JEEnius - IIT Kanpur Alumni · Sep 18, 2026 · 4 min read

Past Paper Solutions

Population Interactions NEET 2026: Answer and Sign Table

Option D explained through NCERT interaction signs, with the predation–commensalism trap and three practice questions.

Founder, JEEnius - IIT Kanpur Alumni · Sep 17, 2026 · 4 min read

Past Paper Solutions

Co-ordination Compounds NEET 2008: Paramagnetism

Work through ligand charges, oxidation states and spin assignments to see why option C is most paramagnetic under the supplied solution.

Founder, JEEnius - IIT Kanpur Alumni · Sep 17, 2026 · 4 min read

Past Paper Solutions

Work, Energy and Power NEET 2012: Stable Equilibrium

Find why r = 2A/B gives stable equilibrium, why U = 0 fails, and how to check potential-energy questions using derivatives.

Founder, JEEnius - IIT Kanpur Alumni · Sep 17, 2026 · 4 min read

Past Paper Solutions

Energy Flow in Ecosystem NEET 2026: 10% Law Explained

Solve the NEET 2026 energy-flow question by separating solar capture from trophic transfer and applying Lindeman’s approximate 10% law.

Founder, JEEnius - IIT Kanpur Alumni · Sep 16, 2026 · 5 min read

Past Paper Solutions

Hydrocarbons NEET 2024: Diborane Question Explained

Solve the NEET 2024 diborane question by tracking the carbon-boron bond and checking each statement independently.

Founder, JEEnius - IIT Kanpur Alumni · Sep 16, 2026 · 4 min read

Past Paper Solutions

Rotational Motion NEET 2012: Cylinder-Spring Solution

A rolling solid cylinder stores 36 J of kinetic energy, giving 0.6 m spring compression when both translation and rotation are counted.

Founder, JEEnius - IIT Kanpur Alumni · Sep 16, 2026 · 4 min read

Past Paper Solutions

Diversity in Living World NEET 2026: Animal Symmetry

Learn why option C is correct by checking radial symmetry and separating adult and larval echinoderm traits, then solve three practice questions.

Founder, JEEnius - IIT Kanpur Alumni · Sep 15, 2026 · 5 min read

Past Paper Solutions

Chemical Kinetics NEET 2024: Activation Energy Solution

Use the two-temperature Arrhenius equation to get 18.22 kJ/mol, select option C and avoid the rounding error that points to D.

Founder, JEEnius - IIT Kanpur Alumni · Sep 15, 2026 · 4 min read

Past Paper Solutions

Lens-Mirror Combination NEET 2012: Why Option C Is Correct

Place the lens focus at the mirror's centre of curvature to get d = 2f1 + f2 and a parallel beam after the final lens passage.

Founder, JEEnius - IIT Kanpur Alumni · Sep 15, 2026 · 5 min read

Past Paper Solutions

Gymnosperms NEET 2026: Answer, Gametophytes and Seeds

Option A is correct: distinguish gametophyte development within sporangia from naked seeds that lack fruit enclosure, not a seed coat.

Founder, JEEnius - IIT Kanpur Alumni · Sep 14, 2026 · 4 min read

Past Paper Solutions

Equilibrium NEET 2025: Phosphoric Acid Question Solved

Solve the NEET 2025 phosphoric acid question using stepwise ionisation constants, acid-strength order and the distinction between option D and statement D.

Founder, JEEnius - IIT Kanpur Alumni · Sep 14, 2026 · 4 min read

Past Paper Solutions

Dual Nature NEET 2012: Threshold Frequency Solution

Find why the threshold frequency is 1.6 x 10^15 Hz and why using the full photon energy gives the wrong option.

Founder, JEEnius - IIT Kanpur Alumni · Sep 14, 2026 · 4 min read

Past Paper Solutions

Structural Organisation NEET 2026: Solanaceae Answer

Check why option A is correct for the Solanaceae question, then practise sepal fusion, stamen attachment and ovary position.

Founder, JEEnius - IIT Kanpur Alumni · Sep 13, 2026 · 4 min read

Past Paper Solutions

D- and f-block elements NEET 2025: Cr²⁺ vs Nd³⁺

Cr²⁺ has four unpaired electrons and Nd³⁺ has three, making option C the correct answer.

Founder, JEEnius - IIT Kanpur Alumni · Sep 13, 2026 · 4 min read

Past Paper Solutions

Lorentz Force NEET 2013: Option C Explained

Option C follows from separating electric and magnetic forces; work through the NEET 2013 solution and three related practice questions.

Founder, JEEnius - IIT Kanpur Alumni · Sep 13, 2026 · 4 min read

Past Paper Solutions

Photorespiration NEET 2026: Why Option B Is Correct

Check why option B is correct using RuBisCO activity, gas exchange, phosphoglycolate formation and ATP/NADPH output.

Founder, JEEnius - IIT Kanpur Alumni · Sep 12, 2026 · 4 min read

Past Paper Solutions

Chemical Bonding NEET 2025: Four Property Orders Explained

Check four property orders using dipole values, xenon electron counting, bond-length comparisons and bond enthalpies to see why only statements A and D are correct.

Founder, JEEnius - IIT Kanpur Alumni · Sep 12, 2026 · 4 min read

Past Paper Solutions

Newton's Law of Cooling NEET 2014: Why the Answer Is 45 °C

Find the 45 °C surroundings temperature using equal-interval excess ratios, check both intervals and identify the error behind option C.

Founder, JEEnius - IIT Kanpur Alumni · Sep 12, 2026 · 4 min read

Past Paper Solutions

Meiosis NEET 2026 Assertion-Reason Question Solved

Official step-by-step solution for the meiosis NEET 2026 assertion-reason question explaining why the correct choice is option C and how to avoid common mistakes in similar NEET biology questions.

Founder, JEEnius - IIT Kanpur Alumni · Sep 11, 2026 · 4 min read

Past Paper Solutions

Reptilia NEET 2026 Assertion-Reason Question Explained

Complete breakdown of the Reptilia NEET 2026 assertion-reason question, official solution, crocodile exception, common mistakes and matching practice questions from Diversity in Living World.

Founder, JEEnius - IIT Kanpur Alumni · Sep 10, 2026 · 4 min read

Past Paper Solutions

Oscillations and Waves NEET 2014: Correct Relation for n

Detailed solution to the NEET 2014 oscillations and waves question on a string divided into three segments, explaining the reciprocal frequency relation with derivation and common pitfalls.

Founder, JEEnius - IIT Kanpur Alumni · Sep 10, 2026 · 3 min read

Past Paper Solutions

Chromosomal Disorders NEET 2026: Both Statements Incorrect

Official step-by-step solution for the NEET 2026 chromosomal disorders assertion-reason question explaining the exact karyotypes of Down's, Turner's and Klinefelter syndromes plus the 45-second solving technique.

Founder, JEEnius - IIT Kanpur Alumni · Sep 9, 2026 · 4 min read

Past Paper Solutions

Natural Selection NEET 2026: Three Patterns and Pitfalls

Breakdown of the NEET 2026 re-held natural selection question showing it produces stabilisation, directional change and disruption but not genetic drift, with method to avoid partial recall errors.

Founder, JEEnius - IIT Kanpur Alumni · Sep 8, 2026 · 4 min read

Past Paper Solutions

Thermodynamics NEET 2024: Vibrational Modes f in Terms of γ

Official step-by-step solution to the NEET 2024 Thermodynamics question on vibrational modes f expressed in terms of γ, with derivation, common mistakes, related problems and 90-second solving strategy.

Founder, JEEnius - IIT Kanpur Alumni · Sep 8, 2026 · 3 min read

Past Paper Solutions

Lac Operon NEET 2026: Only Statement A is Correct

Official step-by-step solution to the Lac Operon NEET 2026 PYQ explaining why only statement A is correct along with common mistakes and must-revise distinctions between regulator and structural genes.

Founder, JEEnius - IIT Kanpur Alumni · Sep 7, 2026 · 4 min read

Past Paper Solutions

Alkynes - Reactions NEET 2025: Propyne Assertion-Reason Solved

Breakdown of the NEET 2025 assertion-reason question on propyne with full stoichiometry, factor-of-10 volume error analysis, practice questions and a 2-minute revision table for terminal alkynes.

Founder, JEEnius - IIT Kanpur Alumni · Sep 7, 2026 · 4 min read

Past Paper Solutions

Polarisation and Malus' Law NEET 2025: Three Polaroids at 22.5°

Official step-by-step solution to the NEET 2025 Malus' law question with three polaroids at 22.5° between crossed polarisers, including visualisation, trig identity and mistakes that lead to distractors.

Founder, JEEnius - IIT Kanpur Alumni · Sep 7, 2026 · 3 min read

Past Paper Solutions

Equilibrium Constant (Kp) NEET 2025: Hard Numerical Solution

Official solution to the hard NEET 2025 equilibrium constant (Kp) numerical shows why Kp equals 1.8 atm and how forgetting the square on P_CO leads many to pick 3 atm.

Founder, JEEnius - IIT Kanpur Alumni · Sep 6, 2026 · 3 min read

Past Paper Solutions

Oscillations and Waves NEET 2025: AQ/AP for Same vmax

Senior faculty breaks down the NEET 2025 oscillations and waves question on two masses with same maximum speed, showing why AQ/AP is sqrt(k1/k2) and how to avoid inversion errors.

Founder, JEEnius - IIT Kanpur Alumni · Sep 6, 2026 · 3 min read

Past Paper Solutions

Thermodynamics NEET 2025: Two Spheres Blackbody Radiation

Breakdown of the hard Thermodynamics NEET 2025 question on two blackbody spheres radiating energy, with full solution, mistake analysis, practice questions and time management tips.

Founder, JEEnius - IIT Kanpur Alumni · Sep 5, 2026 · 3 min read

Past Paper Solutions

Human Evolution NEET 2026: Assertion Reason on Homo Sapiens Origin

Discover the correct way to tackle assertion-reason questions in human evolution for NEET 2026 by verifying statements independently against NCERT textbook lines on Homo sapiens.

Founder, JEEnius - IIT Kanpur Alumni · Sep 4, 2026 · 3 min read

Past Paper Solutions

Boiling Point Elevation NEET 2025: Increasing Order for NaCl and Urea

Senior faculty breaks down the boiling point elevation NEET 2025 question with official solution for ordering NaCl and urea by boiling points, i×C method and practice questions.

Founder, JEEnius - IIT Kanpur Alumni · Sep 4, 2026 · 3 min read

Past Paper Solutions

Atoms and Nuclei NEET 2025: De Broglie Wavelength Ratio in Bohr Model

Step-by-step solution to the hard Atoms and Nuclei NEET 2025 question on de Broglie wavelength ratio in hydrogen Bohr orbits, explaining why answer is 4 not 16 and how to avoid the n-factor error.

Founder, JEEnius - IIT Kanpur Alumni · Sep 4, 2026 · 4 min read

Past Paper Solutions

Correct Statements on Loop of Henle for Human Physiology NEET 2026

This human physiology NEET 2026 article teaches how to evaluate Loop of Henle statements on permeability and reabsorption, spot the correct option a b d, and avoid the common trap of mixing Na+ and water reabsorption.

Founder, JEEnius - IIT Kanpur Alumni · Sep 3, 2026 · 4 min read

Past Paper Solutions

Principles Related NEET 2025: Chlorine Carius Method Numerical

Official step-by-step solution to the hard NEET 2025 chlorine estimation question by Carius method, including why students pick 25% and the exact revision formulas.

Founder, JEEnius - IIT Kanpur Alumni · Sep 3, 2026 · 3 min read

Past Paper Solutions

Genetics and Evolution NEET 2026: Convergent Evolution in Marsupials

Breakdown of why placental mammals and Australian marsupials demonstrate convergent evolution, with official NEET solutions, common mistakes and comparisons to divergent evolution for 2026 prep.

Founder, JEEnius - IIT Kanpur Alumni · Sep 2, 2026 · 3 min read

Past Paper Solutions

Chemical Kinetics NEET 2025: First-Order Isomerization Numerical

NEET 2025 featured a tough Chemical Kinetics question on first-order isomerization requiring calculation of half-life in picoseconds using Arrhenius equation, with the correct answer being 69.

Founder, JEEnius - IIT Kanpur Alumni · Sep 2, 2026 · 3 min read

Past Paper Solutions

Electrostatics NEET 2025: Capacitor Dielectric Charge and Energy

Solution to the NEET 2025 electrostatics question about additional charge and energy change when a K=2 dielectric is inserted into a battery connected capacitor.

Founder, JEEnius - IIT Kanpur Alumni · Sep 2, 2026 · 3 min read

Past Paper Solutions

ABO Blood Group Inheritance NEET 2026: Why D Cannot Produce O Child

Discover why IAIB × IAi cannot produce a blood group O child in ABO blood group inheritance NEET 2026 along with official solutions and 45-second allele-check methods.

Founder, JEEnius - IIT Kanpur Alumni · Sep 1, 2026 · 4 min read

Past Paper Solutions

Heterogeneous Equilibrium NEET 2017: Why the Answer is 5 L

The NEET 2017 heterogeneous equilibrium question on SrO and SrCO3 is solved step-by-step to show why maximum CO2 pressure occurs at exactly 5 L using Kp with constant moles instead of Boyle's law.

Founder, JEEnius - IIT Kanpur Alumni · Sep 1, 2026 · 3 min read

Past Paper Solutions

Lens and Mirror Combination NEET 2025: Object at R/(2μ-1)

Step-by-step solution to the NEET 2025 lens and mirror combination problem with a biconvex lens having one surface polished, explaining the correct object position and common pitfalls.

Founder, JEEnius - IIT Kanpur Alumni · Sep 1, 2026 · 4 min read

Past Paper Solutions

Plant Physiology NEET 2008 Senescence Question Explained

Detailed analysis of the Plant Physiology NEET 2008 senescence question revealing it tests active developmental PCD in xylem differentiation rather than visible ageing like leaf abscission.

Founder, JEEnius - IIT Kanpur Alumni · Aug 29, 2026 · 3 min read

Past Paper Solutions

Density of Crystal Lattice NEET 2018: BCC to FCC Ratio

Official step-by-step solution and error analysis for the NEET 2018 density of crystal lattice question on iron transitioning from BCC to FCC structure while keeping radius constant.

Founder, JEEnius - IIT Kanpur Alumni · Aug 29, 2026 · 3 min read

Past Paper Solutions

Diversity in Living World NEET 2013: Three Correct Statements

Break down the NEET 2013 Diversity in Living World question to identify the three correct statements and master key concepts from bryophytes, pteridophytes and gymnosperms life cycles.

Founder, JEEnius - IIT Kanpur Alumni · Aug 28, 2026 · 4 min read

Past Paper Solutions

Induced Emf and Charge Flow NEET 2017: 32 μC Solution

Detailed solution for the induced emf and charge flow NEET 2017 question explaining why the total charge flow is 32 μC and how time dependence is eliminated in the final answer.

Founder, JEEnius - IIT Kanpur Alumni · Aug 27, 2026 · 4 min read

Past Paper Solutions

Transcription in Prokaryotes NEET 2024: Sigma Factor Question

Breakdown of the 2024 NEET assertion-reason question on prokaryotic transcription, official solution for sigma factor role, common mistakes and NCERT stage mapping to score full marks.

Founder, JEEnius - IIT Kanpur Alumni · Aug 25, 2026 · 3 min read

Past Paper Solutions

Cannizzaro Reaction NEET 2026: Grignard Amine Question

Breakdown of the cyclohexyl magnesium bromide and cyclohexyl amine question from NEET 2026 re-held paper with focus on Cannizzaro reaction NEET 2026 preparation and Grignard reactivity.

Founder, JEEnius - IIT Kanpur Alumni · Aug 25, 2026 · 4 min read

Past Paper Solutions

Chemical Kinetics NEET 2026: Reversible Denaturation Solved

Complete step-by-step solution to the 2026 NEET chemical kinetics reversible protein denaturation question, including the exact ΔS° calculation, distractor analysis, and practice numericals.

Founder, JEEnius - IIT Kanpur Alumni · Aug 24, 2026 · 3 min read

Past Paper Solutions

Organic Compounds Containing Halogens NEET 2026: Radical HBr Addition

Breakdown of a hard NEET 2026 question testing alkyne reduction to geometrical isomers K and L followed by peroxide-effect HBr addition that yields identical racemic M and N.

Founder, JEEnius - IIT Kanpur Alumni · Aug 23, 2026 · 4 min read

Past Paper Solutions

Newton's Laws of Motion NEET 2026: Elastic Collision with Hanging Bob

Complete step-by-step solution for the Newton's Laws of Motion NEET 2026 elastic collision with hanging bob showing why h equals 5 m using NCERT velocity exchange and pendulum energy conservation.