AP Inter 2nd Year Chemistry Model Paper 2027 — Full Paper With Solutions

This model paper follows the official BIEAP pattern for AP Inter 2nd Year Chemistry 2027. Theory: 60 marks in 3 hours. Internal assessment: 40 marks.

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Paper Structure

Section	Type	Questions	Marks
Section A	Very Short Answer (attempt all 10)	10	20
Section B	Short Answer (attempt 4 of 6)	6	20
Section C	Long Answer (attempt 2 of 3)	3	20

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SECTION A — Very Short Answer (2 Marks Each — Attempt All)

Q1. What is rate of reaction? Write its units.

Answer: The rate of reaction is the change in concentration of reactants or products per unit time.
Rate = −Δ[Reactant]/Δt or +Δ[Product]/Δt
Units: mol L⁻¹ s⁻¹ (or mol/L/s)

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Q2. Define half-life period of a first order reaction.

Answer: The time required for the concentration of a reactant to fall to half its initial value is called the half-life period (t₁/₂).
For first order reaction: t₁/₂ = 0.693/k
where k is the rate constant. Half-life is independent of initial concentration for first order reactions.

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Q3. What is a coordination compound? Give one example.

Answer: Coordination compounds are compounds in which a central metal atom or ion is bonded to a definite number of ligands by coordinate bonds.
Example: [Cu(NH₃)₄]²⁺SO₄²⁻ — Tetraamminecopper(II) sulphate
Here Cu²⁺ is the central metal ion and NH₃ are the ligands.

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Q4. Name the type of isomerism shown by [Pt(NH₃)₂Cl₂].

Answer: [Pt(NH₃)₂Cl₂] shows geometrical isomerism (cis-trans isomerism).

• cis-isomer: Both Cl atoms on same side of the square planar complex
• trans-isomer: Cl atoms on opposite sides
  The cis form is used as an anticancer drug (cisplatin).

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Q5. What is meant by denaturation of proteins?

Answer: The process by which a protein loses its native three-dimensional structure (secondary and tertiary structure) due to disruption of non-covalent interactions is called denaturation.
Causes: Heat, change in pH, heavy metal ions, organic solvents.
Example: Boiling of egg — egg white solidifies as proteins denature.

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Q6. Write the IUPAC name of CH₃CHO.

Answer: CH₃CHO is Ethanal (acetaldehyde).

• eth = 2 carbons
• -al = aldehyde group (−CHO)
  The carbonyl carbon is always carbon 1 in aldehydes.

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Q7. What is the difference between primary and secondary amines? Give one example each.

Answer:
Primary amine (1°): One hydrogen of ammonia replaced by alkyl/aryl group.
Example: CH₃NH₂ — Methylamine
Secondary amine (2°): Two hydrogens of ammonia replaced.
Example: (CH₃)₂NH — Dimethylamine

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Q8. What are biodegradable and non-biodegradable polymers? Give one example each.

Answer:
Biodegradable: Polymers that can be broken down by microorganisms in the environment.
Example: PHBV (polyhydroxybutyrate-co-hydroxyvalerate) — used in packaging
Non-biodegradable: Polymers that resist decomposition by microorganisms.
Example: Polythene (polyethylene) — accumulates in environment causing pollution

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Q9. Write the electrode reactions in the electrolysis of dilute H₂SO₄.

Answer:
At cathode (reduction): 2H⁺ + 2e⁻ → H₂↑
At anode (oxidation): 2H₂O → O₂ + 4H⁺ + 4e⁻
Overall: 2H₂O → 2H₂ + O₂
The ratio of gases: H₂:O₂ = 2:1 by volume

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Q10. What are the differences between lyophilic and lyophobic colloids?

Answer:

Property	Lyophilic	Lyophobic
Affinity for dispersion medium	High	Low
Stability	Stable	Less stable
Reversibility	Reversible	Irreversible
Examples	Starch, gelatin, rubber	Gold sol, As₂S₃ sol

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SECTION B — Short Answer (5 Marks Each — Attempt 4 of 6)

Q11. Explain the SN1 and SN2 mechanisms of nucleophilic substitution reactions with examples.

Answer:

SN1 (Substitution Nucleophilic Unimolecular):

• Two-step mechanism; rate depends only on substrate concentration
• Step 1: Ionisation — R−X → R⁺ + X⁻ (slow, rate-determining)
• Step 2: Attack of nucleophile — R⁺ + Nu⁻ → R−Nu (fast)
• Involves carbocation intermediate
• Favoured by: tertiary substrates, polar protic solvents
• Example: (CH₃)₃C−Br + OH⁻ → (CH₃)₃C−OH (tert-butyl bromide)
• Racemisation occurs (both R and S products)

SN2 (Substitution Nucleophilic Bimolecular):

• One-step mechanism; rate depends on both substrate and nucleophile
• Backside attack — nucleophile attacks from opposite side of leaving group
• Transition state with 5 bonds to carbon
• Favoured by: primary substrates, strong nucleophiles, polar aprotic solvents
• Example: CH₃−Br + OH⁻ → CH₃−OH + Br⁻ (methyl bromide)
• Inversion of configuration occurs (Walden inversion)

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Q12. What are carbohydrates? Classify them with examples. Write the importance of glucose in the body.

Answer:

Carbohydrates: Polyhydroxy aldehydes or ketones or compounds that give these on hydrolysis. General formula: Cₙ(H₂O)ₙ

Classification:

1. Monosaccharides — cannot be hydrolysed further
Examples: Glucose (C₆H₁₂O₆), Fructose, Galactose, Ribose (C₅H₁₀O₅)

2. Disaccharides — give two monosaccharides on hydrolysis
Examples:

• Sucrose (glucose + fructose) — table sugar
• Maltose (glucose + glucose)
• Lactose (glucose + galactose) — milk sugar

3. Polysaccharides — give many monosaccharides on hydrolysis
Examples: Starch (storage in plants), Glycogen (storage in animals), Cellulose (structural)

Importance of Glucose:

• Primary source of energy for all body cells (brain exclusively uses glucose)
• Complete oxidation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38 ATP
• Stored as glycogen in liver and muscles
• Blood glucose level is regulated by insulin and glucagon

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SECTION C — Long Answer (10 Marks Each — Attempt 2 of 3)

Q13. Give a detailed account of p-Block elements of Group 16 (Oxygen family). Include: electronic configuration, oxidation states, hydrides, oxides, and important compounds.

Answer:

Group 16 Elements: O, S, Se, Te, Po (chalcogens)

General Electronic Configuration: [Noble gas] ns²np⁴

Oxidation States:

• Oxygen: −2 (most common), −1 (in peroxides H₂O₂), 0 (in OF₂)
• Sulphur: −2, 0, +2, +4, +6 (variable due to vacant d-orbitals)

Hydrides (H₂E):

• All are covalent except for water
• Stability: H₂O > H₂S > H₂Se > H₂Te (decreasing)
• Reducing power: H₂O < H₂S < H₂Se < H₂Te (increasing)
• Acidic strength in water: H₂O < H₂S < H₂Se < H₂Te

Properties of Water (H₂O):

• Bent shape with bond angle 104.5° (due to 2 lone pairs)
• High boiling point (100°C) due to extensive H-bonding
• Maximum density at 4°C

Oxides of Sulphur:

• SO₂ (angular, bond angle 119°) — acidic, used in manufacture of H₂SO₄
• SO₃ (trigonal planar) — reacts with water to form H₂SO₄

Sulphuric Acid (H₂SO₄) — Important Compound:

• Manufactured by Contact Process: 2SO₂ + O₂ → 2SO₃ (V₂O₅ catalyst); SO₃ + H₂SO₄ → H₂S₂O₇ (oleum); H₂S₂O₇ + H₂O → 2H₂SO₄
• Properties: Dehydrating agent, oxidising agent, involatile acid
• Uses: Manufacture of fertilisers, explosives, dyes, storage batteries

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Practice Problems (Self Test)

1. Calculate the rate constant for a first order reaction if 50% of the reactant decomposes in 30 minutes.
2. Write the steps in the preparation of potassium dichromate (K₂Cr₂O₇) from chromite ore.
3. Predict the products and write the mechanism for the reaction of acetaldehyde with HCN.
4. Explain the structure of DNA with a neat diagram.

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Chapter-Wise Weightage

Chapter	Marks
Electrochemistry	8
Chemical Kinetics	8
p-Block Elements (15,16,17,18)	12
d and f Block Elements	8
Coordination Compounds	7
Organic Chemistry (Haloalkanes, Alcohols)	8
Aldehydes and Ketones	7
Amines	5
Biomolecules and Polymers	7

Tip: AP Inter Section A (Very Short Answer) carries 20 marks — that is one-third of the paper. Every answer should be in 2–4 lines maximum. Direct, crisp answers score full marks here.