Chapter-wise PYQ
Class 12 Chemistry

Define the term 'mole fraction'. Calculate the mole fraction of ethanol in a solution prepared by dissolving 46 g of ethanol in 180 g of water.

State and explain Henry's law. Write two applications of Henry's law.

What are ideal and non-ideal solutions? Give one example of each. What are positive and negative deviations from Raoult's law?

What is osmotic pressure? Derive the relationship between osmotic pressure and molar concentration. State van't Hoff factor.

The vapour pressure of water at 20°C is 17.5 mm Hg. Calculate the vapour pressure of water over a solution containing 9 g of urea (mol. mass = 60) dissolved in 180 g of water.

Explain colligative properties with one example each of: (i) relative lowering of vapour pressure (ii) elevation of boiling point (iii) depression of freezing point (iv) osmotic pressure.

State Faraday's laws of electrolysis. Calculate the mass of silver deposited when a current of 5 A is passed for 2 hours. (Atomic mass of Ag = 108, F = 96500 C mol⁻¹)

Define cell constant. How is the conductivity of a solution related to its specific resistance?

Write the Nernst equation for the electrode potential of a metal electrode. Calculate the EMF of the cell: Zn | Zn²⁺(0.1 M) || Cu²⁺(0.01 M) | Cu; E°cell = 1.10 V.

What is a fuel cell? Write the overall reaction that takes place in a hydrogen-oxygen fuel cell. Mention two advantages over conventional cells.

Define molar conductivity. How does the molar conductivity of a strong electrolyte vary with concentration?

Explain the corrosion of iron in the presence of water and oxygen. How can it be prevented by galvanisation?

Define rate of a chemical reaction and rate constant. Write the unit of rate constant for a first-order reaction.

Derive the integrated rate law for a first-order reaction. Show graphically how the concentration varies with time for a first-order reaction.

What is the Arrhenius equation? Explain the effect of temperature on the rate constant. Define activation energy.

The rate constant for a first-order reaction is 60 s⁻¹. Calculate the time taken for 40% of the reactant to decompose.

Distinguish between order and molecularity of a reaction. Give one example where the order differs from molecularity.

Why do transition metals and their compounds act as catalysts? Explain with one example.

Account for the following: (i) Cr²⁺ is a stronger reducing agent than Fe²⁺ (ii) Cu²⁺ is more stable than Cu⁺ in aqueous solution (iii) Zn is not considered a transition element.

Write the preparation and reactions of K₂Cr₂O₇. Describe its oxidising action in acidic medium with one example.

Write the preparation and properties of KMnO₄. Explain its oxidising action in neutral and acidic medium.

What are inner transition elements? Write the general electronic configuration of lanthanoids and explain lanthanoid contraction.

Define: (i) coordination entity (ii) central atom (iii) ligand (iv) coordination number. Give one example in each case.

Explain Werner's theory of coordination compounds. What are primary and secondary valences?

Write the IUPAC name and hybridisation of [Pt(Cl)(NO₂)(NH₃)₂]. Draw the geometric isomers of this complex.

What is crystal field theory? Explain the splitting of d-orbitals in an octahedral crystal field. Distinguish between high-spin and low-spin complexes.

What are chelate complexes? Give one example and state why they are more stable than non-chelate complexes (chelate effect).

Write the IUPAC names of the following: (i) CH₃CH₂CHClCH₃ (ii) ClCH₂CH₂CH₂Cl (iii) bromobenzene

Explain the SN1 and SN2 mechanisms of nucleophilic substitution. How does the nature of the substrate determine which mechanism proceeds?

What is the Finkelstein reaction? Write the reaction for the preparation of iodoethane from chloroethane.

Explain why haloarenes are less reactive than haloalkanes towards nucleophilic substitution.

Explain Lucas test to distinguish between primary, secondary, and tertiary alcohols.

How is phenol prepared from (i) chlorobenzene and (ii) diazonium salt? Why is phenol more acidic than ethanol?

Write chemical equations to show the reaction of ethanol with: (i) sodium metal (ii) conc. H₂SO₄ at 170°C (iii) CH₃COOH in presence of H₂SO₄.

What is Williamson's synthesis? Write the reaction to prepare methoxymethane (dimethyl ether).

Explain Aldol condensation reaction. Give the product when acetaldehyde undergoes intramolecular aldol condensation.

What is Cannizzaro reaction? Give the product when formaldehyde undergoes Cannizzaro reaction.

How will you distinguish between an aldehyde and a ketone using (i) Tollens' reagent and (ii) Fehling's solution?

Write the preparation of carboxylic acid by (i) oxidation of primary alcohols and (ii) Grignard reagent method. Write two reactions of carboxylic acids.

Explain Hell-Volhard-Zelinsky (HVZ) reaction with a suitable example.

Write the preparation of aniline from (i) nitrobenzene and (ii) benzamide. Write the reaction of aniline with (i) HCl and (ii) acetic anhydride.

Why are aliphatic amines stronger bases than aromatic amines? Explain with reference to +I and resonance effects.

What is diazotisation reaction? Write the reaction of aniline with NaNO₂/HCl. What is the Sandmeyer reaction?

How are primary, secondary, and tertiary amines distinguished using Hinsberg's test?

What are reducing sugars? How can you identify whether a sugar is reducing or non-reducing? Give one example of each.

Define: (i) denaturation of proteins (ii) isoelectric point of amino acids (iii) primary structure of proteins.

What are nucleotides? Name the nitrogenous bases present in DNA and RNA. What is the function of DNA?

Distinguish between fibrous and globular proteins. Give two examples of each and mention their biological roles.

What are vitamins? Classify them. Name the diseases caused by the deficiency of Vitamin A and Vitamin C.