JEE doubts
700 doubts found
I keep getting “Oxidation of alcohols” questions wrong in Alcohols, Phenols & Ethers. What's the trap?
trying to oxidise a tertiary alcohol to a ketone or acid.
I keep getting “Acidity of carboxylic acids” questions wrong in Aldehydes, Ketones & Carboxylic Acids. What's the trap?
ranking phenol as more acidic than a carboxylic acid.
I keep getting “Reducing vs non-reducing sugars” questions wrong in Amines & Biomolecules. What's the trap?
assuming every sugar is a reducing sugar.
What is the difference between empirical formula and molecular formula?
The empirical formula is the simplest whole-number ratio of atoms (CH₂O); the molecular formula is the actual count (C₆H₁₂O₆).
What is the difference between orbit and orbital?
An orbit is a fixed Bohr path (outdated); an orbital is a 3-D region of high probability for finding an electron.
What does “Hydrogen bonding” actually mean in Chemical Bonding & Molecular Structure, and why does it matter for JEE?
a strong dipole attraction when H is bonded to N, O or F.
What is the difference between enthalpy and entropy?
Enthalpy is about heat content/energy; entropy is about disorder — spontaneity balances the two through ΔG.
What is the difference between K_c and K_p?
K_c uses molar concentrations; K_p uses partial pressures — they're related by K_p = K_c(RT)^Δn for gases.
How is Redox Reactions tested in JEE, and what should I focus on?
Prioritise the core ideas: Oxidation and reduction, Oxidation number, Oxidising and reducing agents.
What is the difference between atomic radius and ionization energy?
As atomic radius decreases across a period, ionization energy increases — smaller atoms hold their electrons more tightly.
What is the difference between order and molecularity?
Order is experimental and can be zero or fractional; molecularity is the count of species in an elementary step and is always a whole number.
What is the difference between galvanic cell and electrolytic cell?
A galvanic cell produces electricity from a spontaneous reaction; an electrolytic cell consumes electricity to force a non-spontaneous one.
What is the difference between electrophile and nucleophile?
An electrophile accepts an electron pair (e.g. H⁺, NO₂⁺); a nucleophile donates one (e.g. OH⁻, NH₃).
What is the difference between saturated hydrocarbon and unsaturated hydrocarbon?
Saturated means maximum hydrogens and only single bonds; unsaturated has double/triple bonds and fewer hydrogens.
What does “Osmosis” actually mean in Solutions & Colligative Properties, and why does it matter for JEE?
the net movement of solvent through a semipermeable membrane from a dilute (low-solute) side to a concentrated (high-solute) side.
What is the difference between Schottky defect and Frenkel defect?
A Schottky defect is a pair of missing cation+anion (lowers density); a Frenkel defect is an ion displaced to an interstitial site (density unchanged) — seen in ionic solids.
I keep getting “Real vs ideal gas behaviour” questions wrong in States of Matter: Gases. What's the trap?
assuming every gas obeys the ideal equation under all conditions.
What is the difference between monodentate ligand and chelating (polydentate) ligand?
A monodentate ligand donates one pair from one atom (NH₃); a chelating ligand grips the metal at several points (EDTA, ethylenediamine), forming an extra-stable ring.
What is the difference between polar protic solvent and polar aprotic solvent?
A polar protic solvent (water, alcohols) can hydrogen-bond, stabilising a carbocation, so it favours SN1; a polar aprotic solvent (acetone, DMSO) leaves the nucleophile free and reactive, so it favours SN2.
What is the difference between primary alcohol and tertiary alcohol?
A primary alcohol oxidises easily (to an aldehyde/acid) and reacts slowly in the Lucas test; a tertiary alcohol resists oxidation and reacts instantly in the Lucas test (via a stable carbocation).
What is the difference between aldehyde and ketone?
An aldehyde has the carbonyl at the end of the chain (at least one H on it) and is easily oxidised; a ketone has the carbonyl in the middle (two carbon groups) and resists mild oxidation.
What is the difference between aliphatic amine and aromatic amine (aniline)?
An aliphatic amine (e.g. methylamine) has a freely available lone pair and is more basic than ammonia; in aniline the lone pair delocalises into the ring, making it a much weaker base.
What is the difference between molarity and molality?
Molarity is per litre of solution (temperature-dependent); molality is per kg of solvent (temperature-independent).
What is the difference between shell and subshell?
A shell is a principal energy level (n); a subshell (s, p, d, f) is a division within a shell.