JEE doubts
500 doubts found
What does “Limiting reagent” actually mean in Some Basic Concepts (Mole Concept), and why does it matter for JEE?
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 JEE?
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 JEE?
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 JEE?
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 JEE?
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 JEE?
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 JEE?
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 JEE?
the minimum energy barrier reactants must cross; a catalyst lowers it.
What does “Electrode potential” actually mean in Electrochemistry, and why does it matter for JEE?
the tendency of an electrode to gain electrons; cell EMF = E(cathode) − E(anode).
What does “Electrophiles and nucleophiles” actually mean in Organic Chemistry — Basic Concepts, and why does it matter for JEE?
electrophiles are electron-poor (seek electrons); nucleophiles are electron-rich (donate electrons).
What does “Aromaticity” actually mean in Hydrocarbons, and why does it matter for JEE?
extra stability of planar, cyclic, fully-conjugated rings with (4n+2) pi electrons (benzene).
I keep getting “Limiting reagent” questions wrong in Some Basic Concepts (Mole Concept). What's the trap?
assuming the reactant with the smaller mass is limiting.
I keep getting “Filling rules” questions wrong in Structure of Atom. What's the trap?
pairing electrons in a subshell before every orbital has one.
I keep getting “Hybridization” questions wrong in Chemical Bonding & Molecular Structure. What's the trap?
predicting geometry without counting lone pairs in the hybridization.
I keep getting “Gibbs free energy” questions wrong in Chemical Thermodynamics. What's the trap?
judging spontaneity from ΔH alone.
I keep getting “Equilibrium constant” questions wrong in Equilibrium. What's the trap?
including pure solids/liquids in the K expression.
I keep getting “Oxidising and reducing agents” questions wrong in Redox Reactions. What's the trap?
calling the substance that is oxidised the 'oxidising agent'.
I keep getting “Electronegativity” questions wrong in Periodic Table & Periodicity. What's the trap?
assuming metals have high electronegativity.
I keep getting “Activation energy” questions wrong in Chemical Kinetics. What's the trap?
thinking a catalyst changes ΔH or the position of equilibrium.
I keep getting “Electrode potential” questions wrong in Electrochemistry. What's the trap?
forgetting to keep reduction potentials consistent when subtracting.
I keep getting “Electrophiles and nucleophiles” questions wrong in Organic Chemistry — Basic Concepts. What's the trap?
swapping the two definitions.
I keep getting “Aromaticity” questions wrong in Hydrocarbons. What's the trap?
expecting benzene to undergo addition like an alkene.
What does “Concentration terms” actually mean in Some Basic Concepts (Mole Concept), and why does it matter for JEE?
molarity is moles of solute per litre of solution; molality is moles per kilogram of solvent.
What does “Heisenberg uncertainty principle” actually mean in Structure of Atom, and why does it matter for JEE?
you cannot know an electron's exact position and momentum at the same time.