JEE Advanced 2022 previous year paper practice · PYQ-pattern set

JEE Advanced 2022 PYQ-pattern questions

Showing 10 of the 30 PYQ-pattern questions in this set — freshly worded in that year's pattern, not the original questions. Answers and solutions open under each question.

1. Q1 · Mechanics

   A particle of mass m is projected vertically upward with velocity v₀ from the surface of Earth (radius R, mass M). Neglecting air resistance, the maximum height reached above the surface is (given v₀² = gR/3, where g is acceleration due to gravity at surface):

   • A. R/4
   • B. R/5
   • C. R/6
   • D. R/8
   Answer and solution

   Answer: B

   Using energy conservation: (1/2)mv₀² - GMm/R = -GMm/(R+h). With v₀² = gR/3 and g = GM/R², solving gives h = R/5.

2. Q2 · Chemical Thermodynamics

   For a reaction at 300 K, ΔH° = -60 kJ/mol and ΔS° = -200 J/K·mol. The reaction will be spontaneous when:

   • A. Temperature is below 300 K
   • B. Temperature is above 300 K
   • C. Temperature is exactly 300 K
   • D. Never spontaneous
   Answer and solution

   Answer: A

   For spontaneity, ΔG = ΔH - TΔS < 0. Since ΔH is negative and ΔS is negative, the reaction is spontaneous at low temperatures where |ΔH| > |TΔS|. At T = 300 K, ΔG = -60000 - 300(-200) = 0. Below 300 K, ΔG < 0.

3. Q3 · Chemical and Ionic Equilibrium

   The pH of a buffer solution containing 0.1 M CH₃COOH and 0.01 M CH₃COONa is: (pKₐ of CH₃COOH = 4.74)

   • A. 3.74
   • B. 4.74
   • C. 5.74
   • D. 2.74
   Answer and solution

   Answer: A

   Using Henderson-Hasselbalch equation: pH = pKₐ + log([Salt]/[Acid]) = 4.74 + log(0.01/0.1) = 4.74 - 1 = 3.74.

4. Q4 · Hydrogen

   Hydrogen peroxide acts as both an oxidizing and reducing agent. In which of the following reactions does H₂O₂ act as a reducing agent?

   • A. H₂O₂ + 2I⁻ + 2H⁺ → I₂ + 2H₂O
   • B. H₂O₂ + 2Fe²⁺ + 2H⁺ → 2Fe³⁺ + 2H₂O
   • C. H₂O₂ + Ag₂O → 2Ag + H₂O + O₂
   • D. H₂O₂ + PbS → PbSO₄ + H₂O
   Answer and solution

   Answer: C

   In reaction with Ag₂O, H₂O₂ is oxidized (O in -1 state goes to O₂ where O is 0), reducing Ag⁺ to Ag. Hence it acts as a reducing agent.

5. Q5 · Environmental Chemistry

   Which of the following pollutants is primarily responsible for the depletion of ozone layer in the stratosphere?

   • A. Carbon dioxide
   • B. Chlorofluorocarbons
   • C. Sulfur dioxide
   • D. Nitrogen oxides from automobiles
   Answer and solution

   Answer: B

   Chlorofluorocarbons (CFCs) release chlorine radicals in the stratosphere which catalytically destroy ozone molecules, leading to ozone layer depletion.

6. Q6 · Benzene

   Benzene undergoes nitration with a mixture of concentrated HNO₃ and H₂SO₄. The role of H₂SO₄ in this reaction and the actual electrophile generated are:

   • A. Oxidizing agent, NO₃⁺
   • B. Catalyst and proton donor, NO₂⁺
   • C. Dehydrating agent, NO₃⁺
   • D. Reducing agent, NO₂
   Answer and solution

   Answer: B

   Concentrated H₂SO₄ protonates HNO₃ leading to formation of nitronium ion (NO₂⁺), the actual electrophile. H₂SO₄ acts as catalyst and acid.

7. Q7 · Ethers

   An ether with molecular formula C₅H₁₂O is heated with excess hot concentrated HI. It produces two different alkyl iodides which, on treatment with aqueous NaOH, give compounds that both respond positively to the iodoform test. The ether is:

   • A. Methyl-tert-butyl ether
   • B. Ethyl isopropyl ether
   • C. Diethyl methyl ether
   • D. Isopropyl methyl ether
   Answer and solution

   Answer: B

   Ether cleavage with HI gives two alkyl iodides. For both to give iodoform, both must have the –CH₃CH(OH)– structure after hydrolysis. Ethyl isopropyl ether yields ethyl iodide and isopropyl iodide, which form ethanol and isopropanol respectively, both giving positive iodoform tests.

8. Q8 · Phenols

   Phenol is reacted with CO₂ at 400 K under 5 atm pressure in the presence of anhydrous NaOH. The major product formed is then treated with H₂SO₄ to give compound Z. Compound Z is:

   • A. Benzoic acid
   • B. Salicylic acid
   • C. Phthalic acid
   • D. Terephthalic acid
   Answer and solution

   Answer: B

   The Kolbe-Schmitt reaction of phenol with CO₂ and NaOH gives sodium salicylate. Treatment with H₂SO₄ liberates salicylic acid (o-hydroxybenzoic acid).

9. Q9 · Practical Organic Chemistry

   In the Carius method of estimation of bromine, 0.328 g of an organic compound gave 0.376 g of AgBr. What is the percentage of bromine in the compound? (Atomic mass: Ag = 108, Br = 80)

   • A. 32.0%
   • B. 40.0%
   • C. 48.8%
   • D. 51.2%
   Answer and solution

   Answer: C

   AgBr molar mass = 108+80 = 188. Mass of Br = 0.376 × 80/188 = 0.16 g. Percentage = 0.16/0.328 × 100 = 48.8%.

10. Q10 · Biomolecules

    Which of the following statements is correct regarding α-amino acids?

    • A. All amino acids except proline are optically active
    • B. All amino acids except glycine are optically active
    • C. All amino acids are optically active
    • D. All amino acids except lysine are optically active
    Answer and solution

    Answer: B

    Glycine (NH₂CH₂COOH) has no chiral center since the α-carbon is bonded to two hydrogen atoms, making it achiral. All other standard amino acids have a chiral α-carbon and are optically active.