NEET doubts
700 doubts found
I keep getting “Entropy (S)” questions wrong in Chemical Thermodynamics. What's the trap?
thinking entropy always increases for the system alone.
I keep getting “Le Chatelier's principle” questions wrong in Equilibrium. What's the trap?
predicting the wrong direction of shift.
I keep getting “Oxidation number” questions wrong in Redox Reactions. What's the trap?
forgetting that oxidation number can be fractional or zero (e.g. in O₂, it's 0).
I keep getting “Ionization energy” questions wrong in Periodic Table & Periodicity. What's the trap?
ignoring small dips (e.g. B<Be, O<N) caused by sub-shell stability.
I keep getting “Rate constant” questions wrong in Chemical Kinetics. What's the trap?
thinking k depends on concentration.
I keep getting “Anode and cathode” questions wrong in Electrochemistry. What's the trap?
assuming the anode is always the positive terminal.
I keep getting “Resonance” questions wrong in Organic Chemistry — Basic Concepts. What's the trap?
believing the separate resonance structures actually exist and interconvert.
I keep getting “Markovnikov's rule” questions wrong in Hydrocarbons. What's the trap?
reversing it, except in the peroxide (anti-Markovnikov) effect.
Why must the saline drip given to a patient be 'isotonic' and not plain water?
Red blood cells sit in blood plasma of a certain solute concentration.
How does adding a tiny amount of another element (doping) turn silicon into a useful semiconductor?
Pure silicon has few free carriers.
Why do real gases stop obeying PV = nRT at very high pressure or very low temperature?
The ideal-gas law assumes molecules take up no space and don't attract each other.
Why are coordination compounds like chlorophyll and vitamin B12 essential to life?
Both are metal complexes doing specific jobs.
Why does a tertiary halide give a racemic (mixed left/right) product while a primary one gives a single mirror image?
A tertiary halide reacts by SN1 through a flat, planar carbocation.
Why does oxidising a primary alcohol give a different product than a secondary one?
Oxidation removes hydrogens from the C–OH carbon.
Why does a carboxylic acid have a much higher boiling point than an alcohol of similar mass?
Carboxylic acids form especially strong hydrogen bonds — in fact two molecules pair up into a cyclic 'dimer' held by two hydrogen bonds, effectively doubling the particle size.
Why does glucose give a positive Fehling's/Tollens' test but table sugar (sucrose) doesn't?
These tests need a free aldehyde (or α-hydroxy ketone) group that can be oxidised.
What does “Limiting reagent” actually mean in Some Basic Concepts (Mole Concept), and why does it matter for NEET?
the reactant that runs out first and therefore caps how much product forms.
What does “Filling rules” actually mean in Structure of Atom, and why does it matter for NEET?
Aufbau (lowest energy first), Pauli (max two electrons, opposite spins) and Hund (singly fill before pairing).
What does “Hybridization” actually mean in Chemical Bonding & Molecular Structure, and why does it matter for NEET?
atomic orbitals mix to form equivalent hybrid orbitals (sp, sp², sp³) that set the geometry.
What does “Gibbs free energy” actually mean in Chemical Thermodynamics, and why does it matter for NEET?
ΔG = ΔH − TΔS decides spontaneity — negative ΔG means the process is spontaneous.
What does “Equilibrium constant” actually mean in Equilibrium, and why does it matter for NEET?
K compares products to reactants at equilibrium; a large K means products are favoured.
What does “Oxidising and reducing agents” actually mean in Redox Reactions, and why does it matter for NEET?
the oxidising agent gets reduced (gains electrons); the reducing agent gets oxidised (loses electrons).
What does “Electronegativity” actually mean in Periodic Table & Periodicity, and why does it matter for NEET?
an atom's tendency to attract shared electrons; fluorine is the highest.
What does “Activation energy” actually mean in Chemical Kinetics, and why does it matter for NEET?
the minimum energy barrier reactants must cross; a catalyst lowers it.