O₂ has 16 electrons.

MO filling: σ(1s)², σ*(1s)², σ(2s)², σ*(2s)², σ(2pz)², π(2px)² = π(2py)², π*(2px)¹ = π*(2py)¹

Bond order = bonding electrons - antibonding electrons/2​

Bonding electrons = 10, Antibonding electrons = 6 → BO = (10-6)/2 = 2

O₂ has a double bond with 2 unpaired electrons → paramagnetic.

Last updated question 25 feb 2026

A single extraction may not remove all solute.

Repeated extraction with fresh solvent portions improves yield.

The process is done until maximum solute transfer occurs.

Also called repeated liquid-liquid extraction.

Different from fractional distillation (separates liquids by boiling points) and precipitation.

Last updated question 25 feb 2026

Paper chromatography and TLC are mainly for analytical purposes, not large-scale separation.

Column chromatography allows preparative separation of grams of a substance.

The column contains a stationary phase and the sample is eluted with a solvent.

It can handle large volumes compared to thin-layer or paper techniques.

Suitable for both purification and isolation of compounds.

Last updated question 25 feb 2026

Standard deviation measures dispersion of data points.

A small SD → data tightly clustered around mean.

A large SD → data widely spread.

Arithmetic mean measures central tendency, not spread.

Confidence limits give interval estimates, not direct spread.

Last updated question 25 feb 2026

ANOVA = Analysis of Variance.

Used to test whether multiple group means differ significantly.

For two groups, a t-test is sufficient.

ANOVA evaluates variance between and within groups.

It is widely used in experimental and statistical analysis.

Last updated question 25 feb 2026

Colloidal particles often carry surface charges.

These charges attract counterions from the solution, forming the electrical double layer.

Repulsion between similarly charged particles prevents aggregation.

Surface tension alone does not produce electrical repulsion.

Covalent bonding is not relevant for colloidal stability.

Last updated question 25 feb 2026

Chromatography separates compounds based on interaction with stationary phase.

Weak forces like Van der Waals, hydrogen bonding, and dipole interactions affect retention.

Electrostatic forces or chemical bonds are too strong or specific for most chromatography.

The solute moves slower if interactions with stationary phase are stronger.

Hence, Van der Waals forces largely determine solute mobility.

Last updated question 25 feb 2026

Temperature affects kinetic energy of molecules.

Higher T → more collisions exceed activation energy.

Reaction rates typically double for every 10 °C increase.

Pressure or volume changes affect concentration only for gases.

Temperature is therefore the most significant factor in reaction rate.

Last updated question 25 feb 2026

Arrhenius equation: k=Ae^−Ea​/RT

$k$ = rate constant, Ea​ = activation energy, $T$ = temperature.

Increasing T reduces $-E_a/RT$ magnitude → exponential factor increases.

Higher T → more molecules have energy ≥ Eₐ → more successful collisions.

Hence, rate constant increases with temperature, not directly by collision frequency or activation energy.

Last updated question 25 feb 2026

Lattice energy cannot be measured directly.

Born–Haber cycle applies Hess’s law.

It breaks lattice formation into measurable steps.

Uses enthalpy changes like ionization energy and electron affinity.

Hence, lattice energy is calculated indirectly.

Last updated question 25 feb 2026