JEE doubts
700 doubts found
I keep getting “Hydrogen bonding” questions wrong in Chemical Bonding & Molecular Structure. What's the trap?
treating hydrogen bonds as ordinary covalent bonds.
What is the difference between exothermic reaction and endothermic reaction?
Exothermic releases heat (ΔH<0, surroundings warm); endothermic absorbs heat (ΔH>0, surroundings cool).
What is the difference between strong acid and weak acid?
A strong acid ionises completely (HCl); a weak acid ionises only partly (CH₃COOH) and has an equilibrium.
What are the most common mistakes students make in Redox Reactions?
Confusing oxidising/reducing agents, mixing up electron loss/gain, and overlooking zero or fractional oxidation numbers
What is the difference between metals and non-metals?
Metals lose electrons easily (low ionization energy, form cations); non-metals gain electrons (high electronegativity, form anions).
What is the difference between rate and rate constant?
Rate depends on concentration and changes as the reaction proceeds; the rate constant k is fixed at a given temperature.
What is the difference between anode and cathode?
Oxidation occurs at the anode and reduction at the cathode — in every cell, regardless of the terminal signs.
What is the difference between inductive effect and resonance effect?
The inductive effect works through sigma bonds and fades with distance; resonance works through pi systems and can act over long conjugation.
How is Hydrocarbons tested in JEE, and what should I focus on?
Prioritise the core ideas: Saturation, Markovnikov's rule, Aromaticity.
I keep getting “Osmosis” questions wrong in Solutions & Colligative Properties. What's the trap?
thinking the solute moves rather than the solvent.
What is the difference between ionic solid and metallic solid?
An ionic solid is hard and brittle and conducts only when molten/dissolved; a metallic solid is malleable and conducts in the solid state thanks to free electrons.
What is the difference between Boyle's law and Charles's law?
Boyle's law: at constant temperature, pressure and volume are inversely related (PV = constant); Charles's law: at constant pressure, volume is directly proportional to absolute temperature (V/T = constant).
What is the difference between coordinate bond and covalent bond?
A coordinate (dative) bond is a covalent bond where both shared electrons come from the same atom (the ligand); an ordinary covalent bond gets one electron from each atom.
What is the difference between haloalkane and haloarene?
A haloalkane has halogen on an sp³ carbon and readily undergoes substitution; a haloarene has halogen on an aromatic ring where resonance and the sp² C–X bond make substitution much harder.
What is the difference between alcohol and ether?
An alcohol has an O–H group, so it hydrogen-bonds and has a higher boiling point; an ether (C–O–C) has no O–H, so it boils lower and is a common inert solvent.
What is the difference between Tollens' test and Fehling's test?
Both detect aldehydes: Tollens' gives a silver mirror, Fehling's gives a red-brown Cu₂O precipitate — ketones give a negative result in both.
What is the difference between essential amino acid and non-essential amino acid?
Essential amino acids can't be made by the body and must come from food; non-essential ones the body can synthesise itself.
What is the difference between atomic mass and molar mass?
Atomic mass is for one atom (in u); molar mass is for one mole of them (in g/mol) — same number, different units.
What is the difference between Aufbau principle and Hund's rule?
Aufbau decides the ORDER subshells fill (low to high energy); Hund decides HOW electrons spread within a subshell (singly, same spin).
What is the difference between ionic bond and covalent bond?
An ionic bond transfers electrons (metal + non-metal, forms ions); a covalent bond shares electrons (between non-metals).
What is the difference between system and surroundings?
The system is the reaction you study; the surroundings are everything else that can exchange heat/work with it.
What is the difference between adding heat to exothermic and adding heat to endothermic?
Heating an exothermic reaction shifts it backward (toward reactants); heating an endothermic one shifts it forward (toward products).
How do I revise Redox Reactions quickly before the exam?
One-page summary of Oxidation and reduction, Oxidation number, Oxidising and reducing agents, then timed previous-year questions.
What is the difference between group and period?
A group is a vertical column (same valence electrons, similar properties); a period is a horizontal row (same number of shells).