Class 12 Chemistry · 3-Mark PYQ Practice

Focus on Raoult’s law, ideal vs non-ideal behaviour and numerical-type colligative property questions.

1. State Raoult’s law for a binary liquid solution. How is it used to define an ideal solution?
2. Differentiate between ideal and non-ideal solutions on the basis of (i) ΔH_mix (ii) ΔV_mix and (iii) Raoult’s law.
3. State Henry’s law. Mention any two applications of Henry’s law in daily life or industry.
4. Define the following concentration terms: (i) molarity (ii) molality (iii) mole fraction. Write their units.
5. What are colligative properties? Name any four and explain why they depend only on the number of solute particles.
6. Define elevation in boiling point. Derive the relation ΔT_b = K_b m for a solution.
7. Define depression in freezing point. How can it be used to determine the molar mass of a non-volatile solute?
8. What is van’t Hoff factor (i)? How does association and dissociation of solute affect colligative properties?
9. What are azeotropes? Distinguish between minimum boiling and maximum boiling azeotropes with examples.
10. Explain the effect of temperature and pressure on the solubility of (i) gases in liquids and (ii) solids in liquids.

Practice cell notation, EMF calculations and conceptual questions on conductance & corrosion.

1. Differentiate between electrolytic cell and galvanic cell on any three points (direction of electron flow, energy change, electrode polarity, etc.).
2. What is standard electrode potential? How is the standard hydrogen electrode (SHE) used as a reference electrode?
3. Write the Nernst equation for a general electrode reaction. How is it used to calculate the EMF of a cell?
4. Define molar conductivity (Λ_m). How does it vary with concentration for (i) strong electrolytes and (ii) weak electrolytes?
5. State Kohlrausch’s law of independent migration of ions. Give one important application of this law.
6. Explain the terms (i) specific conductivity (κ) (ii) cell constant (G*) and (iii) molar conductivity (Λ_m).
7. Represent the cell notation and write the cell reaction for Daniell cell. How is its EMF calculated from electrode potentials?
8. What is corrosion? Explain the electrochemical theory of rusting of iron.
9. How is the equilibrium constant of a cell reaction related to the standard EMF of the cell? Write the relation and explain symbols.
10. Explain the working of a dry cell or lead storage battery with relevant reactions at the electrodes.

Pay attention to integrated rate equations, half-life formulae and graphical interpretation.

1. Define rate of a reaction. Differentiate between average rate and instantaneous rate of a reaction.
2. Define order and molecularity of a reaction. Give two differences between them.
3. For a first-order reaction, derive the integrated rate equation and show that t_1/2 = 0.693/k.
4. Derive the expression for half-life of a zero-order reaction. How does t_1/2 depend on initial concentration?
5. What is a pseudo-first-order reaction? Explain with the hydrolysis of an ester in acidic medium.
6. State Arrhenius equation. Show how to determine activation energy from a plot of log k vs 1/T.
7. What is activation energy? Explain its role with the help of a potential energy vs reaction coordinate diagram.
8. How does temperature influence the rate of a reaction? Explain on the basis of Arrhenius equation and collision theory.
9. Explain the effect of catalyst on the rate of a reaction. How does it change activation energy and mechanism?
10. From the following data, show how you would determine the order of a reaction with respect to a reactant using initial rates (explain the method; no numerical calculation needed).

Emphasise variable oxidation states, colour, magnetic behaviour and lanthanoid contraction.

1. Give general electronic configuration of transition elements. Why are they called transition elements?
2. Explain why transition metals (i) show variable oxidation states and (ii) form coloured compounds.
3. What is lanthanoid contraction? Mention any two important consequences of lanthanoid contraction.
4. Explain why most transition metal ions are paramagnetic. How is magnetic moment related to number of unpaired electrons?
5. Give any three reasons why transition metals and their compounds are often used as catalysts.
6. Explain the oxidising action of KMnO₄ in acidic medium with the help of suitable ionic equation.
7. Discuss the oxidising action of K₂Cr₂O₇ in acidic medium. Write the relevant ionic equation.
8. Compare the properties of 3d and 4f series elements with respect to (i) shielding effect (ii) complex formation (iii) magnetic behaviour.
9. Why do transition metals form complex compounds so readily? Give any three reasons.
10. Write any three important applications of d-block or f-block elements in industry or medicine.

Practice IUPAC names, drawing structures, predicting hybridisation, geometry and magnetic behaviour.

1. Define the following terms with one example of each: (i) coordination number (ii) ligand (iii) coordination sphere.
2. Write the IUPAC names of any three of the following: [Co(NH₃)₆]Cl₃, K₂[PtCl₆], [Cr(H₂O)₄Cl₂]Cl, [Ni(CO)₄], [Cu(NH₃)₄]SO₄.
3. What is Werner’s theory of coordination compounds? How does it explain primary and secondary valencies?
4. Discuss any three types of isomerism shown by coordination compounds with suitable examples.
5. Explain geometrical isomerism in square planar and octahedral complexes with examples.
6. State the postulates of Crystal Field Theory (CFT). Explain the splitting of d-orbitals in an octahedral crystal field.
7. Draw the crystal field splitting diagram for an octahedral complex. How does it help to distinguish between strong- and weak-field ligands?
8. Predict the hybridisation, geometry and magnetic behaviour (paramagnetic/diamagnetic) of [Fe(CN)₆]⁴⁻ and [FeF₆]³⁻.
9. What is the effective atomic number (EAN) of a central metal ion? Illustrate the concept with one example.
10. Explain the high stability and low reactivity of chelate complexes as compared to complexes with monodentate ligands.